Much of the present day problems are attributable to the fast deterioration of the world’s natural habitat, the environment.  It is undeniably true that human activities along with other several factors, are the top agents of destruction.  As a result, it is still the inhabitants of the earth who continue to face the haunting wrath of mother nature.  Floods, massive soil erosion, global warming, and scarcity of raw materials are just some of the many perils we face. 

Davao City has been the economic and industrial hub of Mindanao for the past several years.  Its growth and progress are immediately apparent due to the infrastructural reforms, high rise buildings, subdivision development, tourism influx and many others.  This is further strengthened by the fact that there has been an increase in the issuance of business permits and other industrial certificates from 1999 to 2000. 

Along with this industrialization comes a great toll on environmental concerns and problems.  With approximately 450 tons of solid waste being disposed everyday, the growing concern on waste management has become an urgent call.  The problem on solid waste creates a vivid reflection of other environmental hazards such as the continued denudation of the forests with Davao having 18% forested area only which is way below the 54% requirement in order to maintain the natural and sufficient  supply of water for consumption. 

True as it may seem,  Davao City has never been spared from the perils of flooding.  Lately, the floods brought by the heavy outpour and even a slight amount of rainfall has caused so much havoc in the tourism and transportation industry.  It has become annoying already.  Several hypotheses have been drawn to answer the persistent question on the causes of these floods.  Studies were also made to define the parameters on making government action to curb the consistently growing flood problem of the city. 

The series of flooding events that affected Davao City in 1999 and the first part of 2000 brought about great concern not only for affected families but for government officials because of the frequency and magnitude of damage which was never experienced locally before. Concern was raised specially on the fact that areas affected were high-density housing subdivisions located within the flood plains of major river basins within Davao City. Numerous questions were raised as to the causes of the floods and what could and should be done to address the hazards of flooding. 

As a result, several measures have already been taken by the local government such as the creation of task forces to monitor and develop programs to solve the flooding insurgency.  As a way of looking into the problem, the drainage plan of 1982 has also been reviewed to adapt to the changing needs of time.  Nevertheless, the problem seems to rise even more.  Hence, this critical analysis on the 1982 Flood and Drainage Plan and the 1998 proposal of Drainage Master Plan of Davao City. 
 

OBJECTIVES OF THE STUDY 

 This study is an  analysis of the 1982 Flood and Drainage Plan of Davao City which has been reviewed and has been integrated in the 1998 proposed Drainage Master Plan of Davao City.  The analysis is undertaken in order: 

1. To identify the key factors and other contributory incidents in the flooding of Davao City ; 
2. To plot, review and analyze the existing flood and drainage plan of  Davao City in its effort to lessen if not eradicate the problem on flooding; and 
3. To make analysis of the flood and drainage master plan and propose recommendations to develop a more responsive master plan; 
4. To identify the strengths and weaknesses at the same time provide recommendatory comments both for the 1982 and 1998  drainage plans; and 
5. To highlight the Talomo River and the Subdivision Developments and other infrastructural projects as major contributors to the flooding incidence in the city. 
 

COVERAGE OF THE STUDY 

 The  analysis shall be limited to the following areas and materials: 

1. The existing Drainage Master Plan of 1982 and the Proposed Master Plan of 1998 for the city of Davao; 
2. The coverage extends only from Toril to Panacan where majority of the commercial, residential and industrial zones are located; 
3. A case highlight of the Talomo River as key factor in the flooding; 
4. A survey on the impact of subdivision development, both low-cost housing and high end development, to the overflowing of rainwater from the drainage canals; and 
5. This study merely uses  the analysis and recommendation framework; 
 

Chapter 2  
DAVAO  CITY:GEOGRAPHY,TOPOGRAPHY  
and ENVIRONMENT 
 

GEOGRAPHY 

Davao City is located in the southeastern part of Mindanao, lying within the grid coordinates  6?58’ to 7?34’ N latitude and 125?14’ 125 40’. The city is approximately 946 aerial kilometers southeast  of Manila and conveniently accessible via 1.5 hours flight planes from Metro Manila. It is accessible from Cebu City, the Visayas premier city, by plane and boat transport,. land, sea and air passenger transport is available to Cagayan de Oro City of Northern Mindanao. 

Because of its strategic location and more advanced infrastructure and amenities, the City is the trade center regionally for Southern Mindanao and intentionally for the Southern Pacific. It is the southern gateway to neighboring countries of Indonesia, Malaysia, Brunei and Australia among others. 

With its land area of 244,000 hectares, Davao City is reputedly the largest city not  only in the Philippines but also in the world. Its area represents about 8% of the total area of Region XI Southern Mindanao. The City is bounded  in the north by the Municipality of Kapalong, Davao Del Norte; in the northeast by the City of Panabo; in the south by the Municipality of Sta. Cruz, Davao del Sur, in the east by the Davao Gulf; in the west by Mt. Apo and North Cotabato; and in the northwest by the Province of Bukidnon. 

The city is partitioned into three congressional districts, which is further subdivided into eleven administrative districts namely: Poblacion and Talomo under Congressional District I; Agdao, Buhangin, Bunawan and Paquibato in Congressional District II and Toril, Tugbok, Calinan, Baguio and Marilog under District III. The administrative districts provide for more efficient and expedient delivery of basic services by the City Government. A total 180 barangays, the smallest political unit, mainly determined by the number of population, comprise the whole city. 

Environmental Conditions 

Considered important environmental factors to the storm drainage study are: climate, topography and soils, land resource and the land use, and water resource. These elements are discussed in the following  sections. 

Climate 

Mindanao Island where the Davao City is located has a tropical  climate. The Island is large enough to give rise to convectional cells, which produce local precipitation almost year-round. The rainfalls from these cells are most common during the warmer months, occurring with attendant thunder and lightning mostly during the afternoon or early evening, when convection is at its maximum. 

The city has a mild tropical climate with no pronounced dry or wet season, suitable for the year-round crop production and vegetative growth. The lowland areas are fairly warm, however, the hinterlands, especially  in the areas of higher elevations, such as Calinan, Baguio, Paquibato and Marilog district experience cooler temperatures throughout the year. 

Mindanao being situated just south of the typhoon belt, makes it  ideal place for culture of fruits and other agricultural crops. The predominant wind direction is northward from the Gulf of Davao where the cooler air of the sea replaces the warm air mass over the City. A surrounding mountain ranges shelter the City from strong winds. 

The average annual rainfall for the past 35 years is 1,750 mm and is fairly evenly distributed through the year. Rainfall is highest in the months of May and June and lowest in December and March. Rainfall occurs in   168 days of the year. 

The annual average temperature is 27.0 C. The variation in mean monthly temperature in a year is small. The changes in temperature on a daily basis are, however, considerable at about 10 C. The mean monthly relative humidity is lowest at 78% in April and highest at 82% in June to August. 

Topography and Drainage 

A substantial part of the City is mountainous, characterized by extensive mountain ranges with uneven distribution of plateaus and lowlands. The mountain range at the western boundary extends as far down as South Cotabato and nestles the Mount Apo, the highest mountain peak in the Philippines at   elevation 3,144 meters above sea level. Mount Apo is considered as semi-active volcano. 

The large and continuous lowland areas of the City are coastal plains and valleys extending inland as gently rising valleys. These areas are found in the eastern part of the City, in Paquibato District, which is an extension of the vast lowlands at the head of Davao Gulf. The other major lowland areas are located in the southeastern part of the City, along the western coast of the Gulf, and comprises the districts of Bunawan, Buhangin, Agdao, Poblacion, Talomo and Toril. These lowland areas are flat to near flat (0 to 3% in slopes). 

Topographically, only the southeast quarter is plain and slightly hilly along the entire coast and uplands north and westwards to Calinan, with slopes of 4 to 5 degrees. The plains and valleys merge gradually into the uplands, and the uplands into mountains. Although, the eastern part of the City is broad lowland belt, it is interspersed by low  hills and knobs. 

The entire land area of the City is drained towards the Davo Gulf. Davao River and its numerous tributaries are the main natural drainage systems. The river originates from Davao del Norte, flows in a southward meandering along the central part of the City and finally flows eastward emptying into the Gulf at the southern periphery of the Poblacion or city proper. A secondary natural drainage is the Talomo River which drains the eastern slopes of Mt. Apo. Other smaller rivers include the Matina River that traverses the middle part of the urban area, the Marapangi Creek in the south and Ilang River in the north. 

Soils 

The soils present a wide variation in color, texture, depth, drainage, relief, permeability and fertility. The soil has been classified by a series of 7 soil groups, that are predominant in the plains and valleys, intermediate uplands, and hills and mountains. 

Land Resource and Land Use 

A vast portion about 77% of the City’s land area is devoted to agriculture. A very small portion or 4% is considered built-up and the remaining 19% are forestland. 

About 28,225 hectares or 11%  of the City’s total land area is identified as the urban zone. The land use zoning of the approximate 28,225 ha urban area as specified in the City’s 25-Year Development Plan. 

Water Resources 

The vast terrain with forest and vegetative cover provides the favorable environment in conserving and storing the rainfall over the large watershed. Surface run-off is minimized as most of the water seeps into the ground. These waters will surface in the lowlands as groundwater or as dry-season flows of the perennial rivers. An example is the Mt. Apo slopes which serves as the water recharge point of the vast groundwater at its foot slopes, like those groundwater reservoirs at Calinan, Toril and Talomo Triangle. 

The abundant groundwater resource is currently tapped as the major source of potable domestic water supply for the City urban populace as well as the large industries. The demand of potable water will increase with the rapid growth in population and increased  industrial activities. The presently untapped surface water will be developed. Groundwater utilization will be controlled to minimize over mining that induces saltwater intrusion, an unfavorable condition that should be prevented. 

There are three major rivers that provide the major drainageway for the city, namely: Davao River, Talomo River and Matina River. Riverflow measurements have been made in these rivers by different government agencies, but these flow records are not available except for Matina River. 

Urban Area Topography 

Under the Davao City Mapping Project in 1994, the City Government of Davao engaged the services of Certeza Surveying and Aerophoto Systems to conduct aerial photography, ground survey and photogrammetric compilation and cartography of the city’s urban area. The output is a 1:4000 scale topographic maps of  the Panacan-Poblacion-Toril area, Calinan and Malabog. Contour intervals are 0.5 m at the coastal plains and 1 m at the higher elevation. 
  

Chapter 3              
THE 1982  URBAN STORM DRAINAGE SYSTEM  

Storm Drainage Master Plan  

The storm drainage master plan for the city’s urban area was developed in 1981-1982 as one of the components of the Regional Cities Development project – a joint undertaking by the city government and line agencies of the national government with funding assistance from the World Bank.  Available reports indicate that the Master Plan is the first documented report on the city’s storm water drainage system.. 

 The Master Plan aimed to rationalize and improve the existing storm drainage conditions and thus relieve the City of expenditures, flood damages and inconveniences resulting from inadequate draining facilities.  The Master Plan provided the area-wide plan for short and long term implementation of main drainage channels, recommended standards and typical engineering designs and set an implementation schedule that would maximize the cost-benefit ration. 

 The coverage of the Master Plan was a 1,390-hectare area on the City’s urban zone which is essentially the coastal strip between the Diversion Road and the Gulf and bounded by the Panacan River in the north and Talomo River in the south.  This urban zone is made up of the areas tabulated in Table 3.1. 

Table 3.1 Natural Catchment Area in the 1982 Drainage Master Plan Study 
 
 
 
 

Drainage Conditions  

The drainage conditions in 1982 were generally not satisfactory. The existing drainage system covers only parts of the existing urban area. The system was constructed over many years, and extensions, are not based on any over all plan which considers future development.. There is no standardization of drain types and drain structures such as manholes, inlets, street crossings, etc. 

The consequences of the inadequate drainage systems are severe flooding in large areas of the Poblacion during storms, presence of stagnant household wastewater at low-lying vacant lots and in obstructed drains, and flooding of roads. These deficiencies cause damages to roads and buildings and represents a hazard to health and a general degradation of the urban environment.  

THE 1982 DRAINAGE CONCEPT  

The 1998 master plan sudy adopts the strategy in the 1982 storm drainage master plan with some revisions that was based on the following principles: 
1. increasing the standard or level of service in consecutive stages of constructions; 
2. a high level of system flexibility to future economic development; and 
3. a high level of resilience against adverse effects of system failures, lack of maintenance, etc. 

The canals or conduits of the present drainage system in the city can be categorized into three levels of service.  Stage 1 consists of unlined open canals that conveys surface run-off from storm as well as sullage.  Stage 2 consists of a lined canal with piped sullage or wastewater.  In Stage 3, the lined open canal is covered and becomes closed conduit, with inlets provided for the inflow of storm and wastewater. 

1982 Drainage Master Plan Areas and Assessment 

The 1982 drainage master plan  layouts are briefly described including their present status. 
 
A. Matina Area- the downstream reaches of the Matina River is meandering. To increase the flow capacity, to “short-cut” channels are proposed at the meandering section of the Matina River just north and south of the MacArthur Highway  as shown. This alternative is found to be more feasible than the extensive dredging  of the riverbed. 

The  proposed cut-off channel consist of a grass-lined trapezoidal canal with 1:1 sideslope, 5 m bottom width and about 3 m depth. The north and south channels are about 100 and 500 meters in lengths respectively.  The proposal includes river training works between the channels and under the bridge. 

 Assessment – The north channel is a component of an on-going residential-resort development proposed in the area but site development has been halted due to the lack of Environmental Clearance Certificate (ECC) from the concerned government authority.  At the downstream south channel, the current urban settlement has encroached on the proposed alignment.  Its implementation will requires a strong political will on the city or national government implementor.   Clearing and relocation on the right of way will likely cause the delay in the construction of the channel. 

B. Quirino Avenue and Roxas Avenue Areas -  A storm drain along Tionko Avenue is proposed to connect to the existing Quirino Avenue main drain, thereby the area around Torres Street will be connected to the system leading to the Davao River.  This drain connection  will reduce the flow to the heavily loaded  Dacudao Main and Agdao Creek.  When the catchment area of the Quirino drain system becomes developed in the future as to cause its overload, the Tionko drain will be connected to the existing Roxas Avenue main drain. 

The existing Roxas Avenue channel drains a rather small catchment area.  The whole area around Jacinto extension, Recto St, Guerrero St., and Bonifacio St., can be drained to the Roxas Main channel.  This will reduce the stormwater flow to the area around Agdao Creek, Sta Ana Avenue, Magsaysay Avenue and Ponce Street.  The most important change in the system is the connection of the drain in Jacinto Extension to Roxas Avenue by a pipe leading from the north of Quirino Avenue along Jacinto Street to Zamora Street and discharging at the beginning of the Roxas Channel. 

Assessment -  Flooding remains at the vicinity of the junction of Jacinto Extension – Torres St.  This is due to the clogged (with garbage), silted canals and the very few number of street inlets to the buried pipe drain at the flooding area. 

C. Dacudau Avenue Area -  The master plan proposed an enlarged and lined channel from JP Laurel to Veloso Street to drain off the areas around Bacaca Road west of JP Laurel Avenue.  Consequently, the main drainage along Veloso Street and Dacudao Avenue are also proposed to be deepened, enlarged and lined.  The existing culverts under the road crossings are proposed to be replaced.  The Dacudao channel will be connected to the Agdao Creek via a 160-meter long double box culvert. 

The proposed scheme will drain  the urban area without major problems provided the lateral drains are properly connected. 

Assessment -  The proposed major sections of the main drain have been implemented, including the cross drain and lined canal from JP Laurel.  The laterals have also been connected to the Dacudao Channel.  The occasional flooding is mainly due to the constrictions at the driveway and road crossings by the prevalent use of small-diameter pipe culverts.  Also uncollected solid wastes find their way into the open canals, thus clogging the cross drains.  Weed growth is abundant in some of the unlined portion of the laterals. 

D. Agdao Creek Area -  The catchment area of Agdao Creek is significantly decreased to 87.4 ha with the diversion of upstream run-offs to the Quirino Avenue and Roxas Avenue main drains. 

The master plan proposes to improve the environmental conditions along the creek by draining off the area with a box culvert located in the upper part of the creek and continued to Soliman Street. 

Assessment – The main drain has been implemented.  Existing laterals appear inadequate due to some flooding in the Sta. Ana Avenue-Sales Street Area.  There is a need to install additional street inlets.  Hydraulic analysis indicated that the pipe drain has adequate capacity. 

E. Lanang  Area -  The 110-hectare Lanang catchment area is characterized by rather steep slopes in the northern parts and a flat area from JP Laurel Avenue to the coast.  In the future, large areas will be urbanized, thus, increasing considerably the amount of stormwater. 

The master plan envisaged the Lanang channel to consist of concrete trapezoidal canal with a bottom width ranging from 3.4-3.5 m at the downstream reach (R. Castillo to Gulf), 2.1-2.3 m at the midstream (JP Laurel to R. Castillo) and 1.1-1.3 m at the upstream (Diversion Roads to Belisario Heights) 

Assessment – At present, the as-built channel at the downstream of the JP Laurel culvert crossing are larger than those envisaged in the 1982 master plan.  Flooding still remains at the vicinity of the Lanang Executive Homes at downstream of the Lanang Golf Course due to flow restrictions by a 200 m section of double  barrel 1800mm diameter RC pipe drain.  Increasing the capacity of this pipe drain by a RC box culvert will require a major construction work.  An alternative is to divert some of the stormwater inflow via the Ubalde Road drain with its upstream end at the Lanang Golf Course. 

F. Insular Area – Large portion in the 1055 ha catchment area of the Insular Channel (or Mamay Creek at upstream)  is planned for residential development.  Its 663 ha upstream area northwest of the Diversion Road is drained by stream tributaries of the Mamay creek.  Downstream of the Diversion Road is drained by stream tributaries of the Mamay Creek.  Downstream of the Diversion Road, the Creek traverses residential areas until it crosses the JP Laurel Avenue and henceforth, the Insular Channel that outlets to the gulf. 

The existing  culverts crossing the Diversion Road and Laurel Avenue have adequate capacity for the fully developed area, including the recently lined Insular channel.  The master plan envisages widening, deepening and lining of the existing Creek. 

Assessment – The creek width have been diminished by the encroachment of the residential lots.  This is the case of Fortune Executive Homes, where the wide lined channel become restricted for some 600 m along the village periphery.  Considering the difficulty in the widening of the constricted canal by the encroachment of residential lots, a box drain routed below the existing subdivision road will provide an alternate channel, whose design was completed and proposed for construction with other priority drainage projects.  At the upstream of the Mamay Creek, the creek follows a meandering route and the area suffers frequent inundation. 
 
 
Chapter 4    
THE PROPOSED 1998 MASTER PLAN  
  

EVALUATION OF THE FLOOD PRONE AREAS  

Taking into considerations, the existing drainage systems, the 1982 storm drainage master plan and the established planning and design criteria, described in the previous sections, a drainage master plan was formulated for the city’s urban areas. 

An evaluation of the topographic maps and the general drainage patterns help identify the flood prone areas in the study area.  These are the strip of floodplains adjoining the coastline of Davao Gulf and extend from Panacan in the north to Toril in the South.  The presence of a road network and transport systems, made these areas the focus of urban development and growth.  The industries are located in the North, while the Poblacion located midway is the center of the commerce and residential settlements; and prime residential and resort development are centered in the south floodplains. 

From the identified flood-prone areas, the critical sites were selected and have the following characteristics: 

· There is a frequent flooding based on the reports and complaints by local residents to concerned authorities; 
· There exists no well defined major drainage waterway and the apparent waterway is being encroached by rapidly growing settlements; 
· There are predominantly open spaces and a very high growth potential 
· The flooding impedes the transport of goods and people in a major road entry. 
 

The extensive analysis and field investigation indicated the following growth centers with critical need for a drainage plan: 

1. Lizada, Toril District 
2. Dumoy, Talomo District 
3. Matina Aplaya, Talomo District 
4. Ma-a, Talomo District 
5. Barangay Buhangin Proper, Buhangin District 
6. Panacan, Bunawan District 

ThePoblacion area was the focal point of the 1982 urban drainage master plan and the major recipient of the urban drainage constructions under the Regional Center Development Project in the early 1980s to early 1990s. 

The proposed drainage master plan provides the general layout of the proposed mains and drains for selected sites.  The plan includes typical preliminary designs and standard details.  The hydraulic and hydrologic calculations were conducted to establish the design flood flows and the sizes of the proposed drainage mains and structures. 

A. Lizada Area Drainage 

Lizada is situated in the southwestern part of Davao City.  It has generally mildly sloping terrain with some slight changes in elevation in isolated areas.  The area has a total catchment area of about 226 ha.  It is characterized as highly protected residential zone with areas near McArthur highway as major commercial zones and areas near the Davao Gulf as protected light and medium industrial zones. 

The existing drainage facilities in the Lizada are mostly earth canals.  Lined canals are found in quite a few areas such as the Christian Homes Subdivision.  These facilities are capable only of limiting flooding in certain areas up to a certain extent.  Based on actual field surveys, the capacities of these drainage facilities are inadequate in containing a considerable volume of stromwater especially during heavy rains. 

Recommendation -  2 main drains of trapezoidal masonry canal type are proposed for the Lizada area.  The immediate impact is to alleviate severe flooding  in the flood prone areas of Mabisa Colosa and the eastern part of the Tambakan Road area.  The area is expected to be developed into residential and commercial and even industrial zones in the near future based on the city’s land map use.  With the construction of the main drains,  and their respective laterals, the open areas in Barrio Lizada formerly unfit for development due to severe flooding will now be available for development.  This will eventually result in the increased land values in the area. 

B. Dumoy Area 

Dumoy is also located in the southwestern portion of the City.  The terrain area is steep in the northern part with an elevations ranging from 7 to 20 m above msl followed by a relatively flat contour in the southern portion down the coast. 

Majority of the existing drainage  facilities in Dumoy are lined and earth canals found along the MacArthur Highway and inside the various subdivisions and open areas located in the area.  However, most of these canals arediscontinuous, leaving storm run-off properly drained to its intended outfall.  For this area, 3 drainage canals are to be designed of trapezoidal masonry type. 

Recommendations – Existing earth canals inside affected subdivisions and areas along the Mac Arcthur Highway should be improved and cleaned of obstructions and debris in order to maximize the capacities in collecting stormwater.   The area has a very strong potential for residential growth as well as commercial development as manifested by the various commercial establishments found along the MacARthur Highway aside from the number of subdivisions located in the area such as the IWHA Village, Better Living, Greenland, and Fairland Subdivisions.  There are also many open areas and farmlands which have yet to be developed.  Addressing the problem of flooding would not only increase land values but also provide developers the chance to utilize the areas.  The problem that may be encountered in the constriction of the drainage canals is that the existing lined canals in the fishpond areas may not be able to accommodate the volume of stormwater coming from upstream. 
 
C. Matina Aplaya Drainage Area 

Matina Aplaya is locate in the southern portion of the City.    The area is generally considered to be flat as it is composed mostly of residential subdivisions.  Existing drainage facilities found in the area are mostly masonry concrete lined and earth canals along Matina Aplaya Road and Quimpo Blvd. Majority of the subdivisions in the area have well defined drainage systems.  However, the presence of garbage and other debris blocking the drainage ways and the absence of a main drainage outlet have caused these drainage facilities to be ineffective in draining storm runoff properly.  This has resulted to the ponding of stormwater and the incidence of flashflooding in some areas. 

Recommendations – There are also 3 main drains proposed for this area which is of trapezoidal masonry type designed to collect stormwater from a catchment area.  There shall also be rehabilitation of existing canals located at the back of NHA Alpha Homes.  The existing canal is currently blocked with garbage and other debris particularly in the pipe culverts.  Since this is highly residential area, the construction of the drains will provide an outlet for the considerable volume of runoff coming from various subdivisions found in the area. 

D. Ma-a Drainage Area 

Ma-a is situated in the central portion of Davao City.  It has generally a rolling terrain with steep contours in the northern and western portion of the study area respectively.  It is classified mostly as a residential zones, with densities varying from medium to high.  Major commercial zones are located near Ma-a and Diversion Roads while some industrial zones are scattered. 

Drainage facilities in Ma-a include lined canals, which are mostly located along the Ma-a road. Natural creeks and earth canals also make up the existing drainage system in the area.  Other drainage structures include box and pipe culverts. 

However some residential zones, located in low lying areas adjoining the Davao River experience flooding especially during rainy season due to inadequate drainage facilities to contain storm runoff coming from upstream. 

Recommendations – 2 main drains are proposed for this area designed to collect a runoff coming mostly from the western portion and the upper portion of the diversion road.  This area is seen to have high potential for commercial growth and residential development as seen in the on-going development of Monteritz Estates and Woodridge Subdivision. 

E. Buhangin Proper Area 

Buhangin is located in the northern part of Davao City.  The general topography of the study area is characterized by rolling terrain  with the northern, eastern, and western parts having steep contours. 

Existing drainage canals found in Brgy Buhangin Proper are mostly earth canals with some lined canals located in the northern, eastern and western part of the area.  Run off coming from the Villa Park Subdivision and the proposed memorial park are collected through the main earth canals.  These canals converge to form a singular canal which will then  direct the stormwater towards Mamay creek channel.  However, the existing earth canals are incapable of containing stormwater effectively. 

Recommendation – Only one main drain is proposed with a total length of 0.7 km.  It will start from Cabantian Road which is right across a proposed memorial park.  The drainage channel will eventually connect with the Mamay Creek.  The flooding in this area is attributable to the  natural geography of the area and the inadequacy of the capacities of the existing drainage facilities to contain runoff coming from the Villa Park Subdivision and the proposed memorial park area. 
 
F. Panacan Area Drainage 

Panacan is situated in the eastern portion of Davao City.  The area is characterized by rolling terrain with some areas having steep contours. Areas near the coastline have mild slopes. 

The existing drainage facilities in the area are mostly lined and earth canals.  These facilities are located in selected areas along the highway and some residential areas like Sarmiento and Luzville Subdivision.  These facilities, aside from being very limited in number, are also ineffective in containing stormwater coming from upstream because majority of them are clogged with garbage and debris.  The natural waterways found in the area are:  Panacan River, Awad Creek and Ilang Creek. 

Recommendations – 2 main drains are proposed in this area which will involve rehabilitation or improvement of the existing earth canal.  This facility is currently clogged.  In addition, 2 lateral drains shall be designed along Panacan Road.  The existing canal in front of V+L Ventures should be enlarged and lined up in order to improve its capacity in draining storm runoff towards the Davao Gulf.  It should also be cleared from garbage and other obstructions constricting the flow of water towards the outfall.  The junction of the Diversion Road and Panacan Road is considered to be a flood prone area.  Because of the inadequate drainage facilities in the area, the volume of runoff coming from upstream cannot be controlled and drained properly to its intended outfall. As a result, floodwater tends to spread over the Diversion and Panacan Roads which impedes transfer of goods and people. 
  

THE PROPOSED SEWERAGE SYSTEM  

Under a World Bank Grant, the City is one of the 5 cities outside Metro Manila selected for sanitation and sewerage planning in 1993 feasibility study to formulate a National Sanitation and Sewerage Sector Strategy.  The 1993 Sewerage plan which is an improvement of the 1982 plan, was updated in 1996, with focus on investment and institutional arrangements to implement the city’s project. 

The sewerage scheme formulated in 1982 drainage master plan aimed to address the growing sewage disposal and sanitation problem in the city’s urban area.  The scheme foresees a centralized sewerage system with intercepting sewer mains linking the existing storm drainage system to a number of simple treatment plants and final disposal of the treated wastewater to the sea outfall.  The proposal consists the following features: 

· Two sewerage plants each located at Dumalag Point and Lanang; 
· Combined main drains each at Talomo, Matina, Poblacion (3points), Agdao, Lanang and Insular; and 
· Intercepting sewer mains to the combined main drains. 

However, at present there exist no sewerage system in the City.  The drainage plans are supposed to allow future integration of a sewerage system aimed at reducing the risk of health hazards and the pollution in the coastal zones. 
 
  

Chapter 5  
THE TALOMO RIVER STUDY  

Drainage Pattern  

Talomo River is one of the primary drainage systems in the Mt. Talomo area.  Its watershed covers an approximate area of 26,735 hectares.  It originates from the headwaters of Mt. Talomo then passing through the districts of Calinan, Mintal and Talomo before finally exiting to Davao Gulf area.   From the headwaters of Mt. Talomo, the river is characteristically northeast in orientation along with its many tributaries.  But as the river reaches the relative flatter ground, the course of the river is deflected almost at right angle to a southeast direction.  The closely-spaced and parallel direction of the drainage systems in Mt. Talomo appear to be controlled by the orientation of the underlying rock formation, specifically by the bedding orientation of the sedimentary formation.   The 90º-deflection of the course of the river as it approaches the flat-lying ground, on the other hand, seem to be controlled by a parallel geologic structure, possibly a fault system. 

Within the watershed, Talomo River, along with its tributaries appear to form a parallel to trellis drainage patter.  But altogether, the river systems that drains Mt. Talomo form a radial pattern. 

Talomo River is considered to be on a stage of maturity as characterized by wide meandering flow, wide flood plains and moderately-steep incised river valleys.  However, the headwaters of Talomo River appear to still be on a youthful stage because of the relatively more linear flow, narrow or absence of flood plains and deeply incised river valleys.  This is another evidence of the existence of a possible fault at the point where the river changes from a youthful stage to a mature one. 
 
 
Lithology/Geology  

Three lithological units were identified within the watershed.  The youngest unit is the recent alluvial deposits and terrace gravels that are distributed mostly in the lower portions of Mt. Talomo.  This unit is composed mainly of unconsolidated sediments from boulders to clay sizes that were transported from the slopes of Mt. Talomo.  The second unit is made up of lava flows, pyroclastic flows and other volcanic ejecta from the old eruptions of Mt. Talomo that are distributed mostly along the upper foothills in the central portion of the area.  The third unit consists of the andesite and dacite plugs near the top of Mt. Talomo which presently is a non-active volcanic dome. 

Rainfall Pattern/Data  

At present, no actual rainfall data is established for the Talomo Watershed.  The PAG-ASA rain gauge station  located within PCA compound at Bago Oshiro in Mintal, which covers the Bago River Watershed, is being used to estimate the rainfall of the adjacent Talomo Watershed.  However, this method will not produce a realistic analysis of the flooding within the Talomo Watershed. 

Another data used for flooding analysis is the mean discharge and minimum and maximum gauge heights of the Talomo River measured at a DPWH station located at Brgy. Tugbok, Davao City.  

History of Flooding  

Throughout the history of Talomo River, several occurrences of flooding had been experienced.  This is evident from the development of wide alluvial plains or specifically, flood plains, along the banks of Talomo River.  These flat-lying areas are presently being utilized for residential, commercial and light industrial purposes.  And because these areas are considered to be flood plains, it is expected that they will continually be affected with floods in the future. 

May 24, 1995 Brgy. Talomo 
 
June 20, 1995 Sto. Niño, Tugbok 
 
April 26-28, 1996 Talomo Area including: 
 - Purok 1 & 2, Talomo Proper- Talusa, Brgy. Talomo- Taal, Bangkal- Bulusan- Cadena de Amor- San Juan & San Roque- Dela Merced- Purok 13, Brgy. Ma-a (Riverside) 146130196121422377626 
 
April 26-28, 1996 Tugbok District including:- Km. 20- Purok 3- Quarry- Brgy. Balingaang 40257 
 
April 26-28, 1996 Calinan District including:- Brgy. Dalagdag- Brgy. Riverside 1424 
 
July 10, 1996 Sunny VillageTeacher’s Village 120 
 
January 28-31, 1997 Talomo District including:- Talomo- Matina Crossing- Bago Aplaya- Bago Gallera 52310063- 
 
January 28-31, 1997 Calinan District including:- Riverside- Subasta- Calinan Poblacion- Wargan- Ramayong 4475-- 
 
January 28-31, 1997 Tugbok District including:- Sto. Niño- Los Amigos- Balengang- Talancang 196--- 
 
April 25, 1997 - Brgy. 74-A, Matina Crossing- Talomo Proper- Matina Pangi- Matina Aplaya 301013- 
 
June 25, 1997 Sitio Dumanlag, Matina 2 
 
July 9, 1997 Talomo District including:- Sitio Taal, Talomo- Sitio Bulusan, Talomo- Teacher’s Village, Bangkal- NHA, Bangkal- Royal Valley, Bangkal- Sto. Niño, Mintal, Tugbok District 
 
September 3, 1998 Talomo District including:- Crossing Ulas- Brgy. Talomo 
 

On the 16th of February 2000, several areas in Davao City were devastated by floods and were declared at a state of calamity.  Several parts along Talomo River which includes Talomo, Tugbok and Calinan Districts were among the areas that were hardest hit. 

The following lists the reported damage during the calamity: 
Areas Affected No. of Families Partially Damaged Totally Damaged 
Calinan District:1. Calinan Proper-     Purok 15, 16 & 172.   Riverside 53 families 
 
Tugbok District:1. Mintal Proper2. Tugbok Proper3. Los Amigos-      Purok 1 to 84. New Carmen-      Sitio Uyon 2, Purok 3 111 families 6 houses 4 houses 
 
Talomo District:1. Balusong2. Talomo Proper- Blk. 1 Brgy. Talomo- Purok 13, Brgy. Talomo- Purok 14, Brgy. Talomo- Purok Saloroja- Purok Talosa- Purok Washington- San Lorenzo - Salakot- Semento3. Matina- Bulusan, Sto. Niño4. Bago Aplaya- Seaside5. Bago Gallera- Purok 8, Seaside6. Matina Aplaya- Purok Shanghai7. Matina Pangi- Km. 5,6 & 9- Guadalupe8. Bangkal- NHA Kadayawan Phase III- SM Village- Taal St.- Makiling St., Central Park, Bangkal- Royal Valley Subdivision- Talomo Muslim Village- Ortega Village9. Ulas- Sunnyville Subdivision- Teacher’s Village10. Ma-a- Datu Loho Village- Sanggilangan Muslim Co.- San Rafael Village11. Matina Crossing- New Visayas Riverside12. Puan13. Gulf View Subdivision14. IWHA Subdivision 250 families12 families120 families130 families90 families150 families120 families9 families30 families54 families300 families200 families300 families15 families15-20 families140 families148 families22 families 1 house 3 houses3 houses6 houses9 houses2 houses1 house2 houses22 houses 
  

Causes of Flooding  

In evaluating the causes of flooding within the Talomo River Basin, it is important that we understand that natural environment where the flooding occurs.  The area of Brgy. Talomo and its vicinity is considered to be situated on top of a broad alluvial plain that developed from flooding events in the history of the Talomo River.  These areas are referred to as flood plains.  It is therefore important that we accept the fact that, historically, the area has been affected by flooding and will continue to be affected by flooding in the future.  What may have changed, possibly is the intensity and frequency of flood occurrences. 

Through the course of the study  based on available data and field inspection, several factors were identified that in one way or another, have contributed in intensifying the flooding experienced within the Talomo Watershed. 
 

FLOOD-INTENSIFYING FACTORS:  

1. Excessive Rainfall 

Based on historical record, the middle of the year from the month of May and June, produces the highest precipitation of more than 250 mm rainfall.  The early parts of the year, on the other hand, are the dry months where precipitation is limited to less than 150 mm rainfall. 
 However, on February of this year, a devastating flood took place affecting a great area of Talomo District as well as other areas within the watershed.  The monthly precipitation as measured from the Bago Oshiro station was 392 mm which is more than twice the average monthly precipitation from historical records. 

2. Basin Shape 

The shape of the basin is also being considered here to be one flood-intensifying factor.  Because of the east west elongation of the basin that drains to the east, rain that originates from the west and moving easterly is likely to produce intensified runoff and cause bigger floods than rain that originates from the east and moving westerly. 

3. River Channel Shape 

Two segments along the Talomo River is experiencing flooding due to its characteristic river channel shape.  The first is in the area of Tugbok where the flow of the river is noticeably deflected from a northeast direction to a south-southeast one.  During periods of high discharge rate, this deflection can cause river to overflow at this portion. 

The second area is in the down stream portion of the river where the natural flow of the river is widely meandering.  This segment of the river similarly causes overflowing when water hits major bends. 
 
4. Loss of Vegetative Cover 

The loss of vegetative cover probably has one of the greatest impact on the flooding incidents in Talomo Basin.  To begin with, the loss of vegetation causes runoff to increase where most of the rainwater goes directly to the river.  It also shortens the time to which water flows from the slopes to the river, in effect increasing the rate of stream flow (flash floods) 

Another consequence of the loss of vegetative cover is the increase in the sediment load of the river.  The sediments in turn sometimes causes the depth of the river to be significantly reduced and flooding can occur (siltation).  This was observed at the mouth of the Talomo River where a sandpit is starting to form. 

5. Underlying Soil and Rock 

The underlying soil and rock formation controls the amount of rainfall that goes into the ground (infiltration) and the amount that forms the runoff (surficial water).  The underlying soil materials in the area are composed mainly of fine sediments in the silt and clay sizes.  This type of soils have very limited permeability and does not easily allow water to infiltrate.  Most of the rainwater, therefore, contributes to the runoff. 

The underlying rocks likewise are of low permeability and most of the rainwater is also converted into runoff. 

6. Sediment Load 

The amount of sediment load of the river is also being considered to be contributory in the flooding incidents because most of the sediment that is deposited at the down stream portion of the river causes siltation resulting to considerable decrease in depth of the river. 

7. Human Influence 

Because of the rapid growth of the city, a great portion of the land is being claimed by development.  These developments include both residential and commercial conversions of former agricultural and/or forest lands.  These developments reduce the vegetative cover in the area and consequently causes flooding. 

Riverbanks have also been targets of development where sometimes, huge structures are put up that constricts the flow of the river and therefore causes flooding. 

Dams for electrical power have also been constructed along the stretch of the river.  However, there is not enough data to determine how much impact it has on the flooding incidents in the area.  This factor has to be studied in greater detail. 

It is important for people to realize that some of the areas identified as susceptible to flooding sits on top of flood plains that in the course of the history of Talomo River has been constantly affected by flooding.  It is only now that the impact of flooding is greatly felt because of the damage it has brought on lives and properties, primarily because of great increase in population and changing land use. 

Several factors were identified that may have, in one way or another, contributed in intensifying the flooding in the area as mentioned earlier in the report.  The next step, therefore, should be aimed at identifying measures, whether natural or man-made, that can address these factors and in effect limit the impact of flooding on the areas constantly affected. 
 

Recommendation 

Flood Control Measures 

Some of the factors that were earlier identified are beyond the control of man like the amount of rainfall and basin shape.  However, the rest of the factors are within the control of man and technology.  These factors should be the target of flood control measures. 
 
Reforestation of the watershed should be a primary measure to be undertaken.  Reforestation alone is likely to be able to address several factors already identified like increased sediment load and increased percent runoff as well as runoff rate and stream flow rate. 

Engineering measures could likewise be utilized in redirecting the river channel to be less favorable to flooding by limiting removing the major bends that serve as obstacle to the natural stream flow.  Man-made obstacles to the natural stream flow should likewise be removed. 

Also, in understanding the hydrology of a river basin like the Talomo River, proper data collection and analysis should be undertaken.  The previous flood experiences that we have encountered should signal the need for proper monitoring of the river basin.  Perhaps a hydrologic study to cover the Talomo River Basin could be initiated as a start. 
 
   

Chapter 6      
THE HOUSING AND SUBDIVISION DEVELOPMENT CASE  
 

A.  THE HLURB 

 The Housing and Land Use Regulatory Board is the administrative agency having jurisdiction in the following cases, viz: 

1. Unsound real estate business practices; 

2. Claims involving refund by subdivision lot or condominium unit buyers against subdivision developers, owners, dealers, agents, brokers and salespersons; 

3. Actions for specific performance of a contractual or obligatory nature filed by subdivision lot or condominium unit buyers against subdivision developers, owners, dealers, agents, brokers and salespersons; and 

4. All actions, applications and protests involving the issuance of licenses, permits and clearance for the development of lands and subdivision areas. 

 In line with the HLURB’s fourth area of jurisdiction,  the following are the  requirements in order to develop a subdivision, among others: 

8.  A certified true copy of the Environmental Compliance Certificate or the Certificate of Exemption therefrom issued by the Department of Environment and Natural Resources; 

9. Special Requirement 

9.1  For subdivision project only 
  Survey plan verified and approved by the Land Management 
  Bureau or duly received by said office 

9.2  For condominium project only 
Plans registered with the Register of Deeds including the Master Deed and the Declaration of Registration 

10. Additional requirements (original or certified true copy) in case the subdivision approval is made by the local government) 

10.1 Sanggunian Resolution or ordinance approving the subdivision plan for the project and/or the development permit or its equivalent 
10.2 Subdivision plan approved by the local government unit showing all proposals (roads and alleys and date pertinent thereto, lot and block numbers and areas, and site data) including tree planting 
10.3 Engineering plans (alignment, elevations, typical cross sections and details of systems for road, water, drainage and sewage disposal, power distribution and street lighting) 
10.4 Topographic plan 
10.5 Project study 
10.6 Recent tax declaration 
10.7 Permit to operate a deepwell and a water resistivity test, if necessary 
10.8 In case the approval is with housing, all housing models, bill of materials and cost estimates 
 
 

B.  REVISED MINIMUM DESIGN STANDARDS FOR PD 957 AND BP 220 

PARAMETERS PD 957OPEN MARKET HOUSING BP 220ECONOM ICHOUSING BP 220SOCIALIZED HOUSING 

Drainage System Underground Underground for major roads lined open canal (for other roads) Lined open canal (sides of open canal shall be lined with stone rip-rap) 
 The drainage system must conform with the natural drainage pattern of the subdivision site, and shall drain into appropriate water bodies, public drainage system or natural outfalls. 
 

C.  PLANNING AND DESIGN STANDARDS FOR A RESIDENTIAL SUBDIVISION PROJECT 

PARAMETERS PD 957OPEN MARKET HOUSING 
Project location Within suitable sites for housing and outside potential hazard prone and protection areas. 
Drainage  UNDERGROUNDThe drainage system must conform to the natural drainage pattern of the subdivision site, and shall drain into appropriate water bodies, public drainage system or natural outfalls. 
Sewerage Disposal Systema.  Septic Tankb.  Connection to Community Sewer System Individual septic tank conforming to standard design of the Sanitation CodeWhenever applicable, connections shall be made to an approved public or community sewer system subject to the requirements and provisions of the Sanitation Code and other applicable rules and regulations with regards to materials and installation practices. 
Garbage Disposal System Provide sanitary and efficient refuse collection and disposal system whether independently or in conjunction with the local government garbage collection and disposal services. 
 

D. EXECUTIVE ORDER NO. 23 

Executive Order No. 23 is an order creating and constituting a permanent task force to monitor the drainage problem in the City of Davao.  The Task Force was created by the Mayor of Davao City, Benjamin C. De Guzman, on the 3rd day of July 2000. 

Executive Order No. 23 was enacted due to the following, as found in its WHEREAS clauses: 

1. One of the problems now besetting the City is the occurrence of flashfloods particularly in the Poblacion area and in the subdivisions. 

2. There is a need to monitor the drainage problem in the City especially during heavy rains to prevent damage to life and property. 

3. Task Force La Verna was earlier created but its duties and functions were solely confined to determining the causes of the flooding at the La Verna Subdivision. 

4.  Task Force La Verna has rendered its final report to the City Mayor and is now deemed dissolved for all intents and purposes. 

The permanent Task Force to monitor the drainage problem in the City of Davao is composed of the City Mayor as Chairman, the City Administrator as Vice Chairman.  The members are the City Engineer, the Regional Director, DPWH Region XI, District Engineer, DPWH, Regional Director, DENR, Officer-in-Charge, Housing and Urban Development Coordinating Council, and the Regional Officer of the HLURB.  In the minutes of one of the permanent Task Force’s meetings, the City Planning was later on added to the roster of its members. 

The main function of the Task Force is to evaluate all the areas affected by flooding and submit periodic reports and recommendations to the City mayor.  The funds necessary for this will be provided by the local government of Davao City. 
 

E. DRAINAGE OUTLETS 

    Drainage systems shall be designed and constructed such that their outlets are rivers, lakes, the sea, natural bodies of water or such other water courses with the following requirements: 

a. Hydraulic control structures, such as flap gates or drainage gates shall be provided to prevent back flow during high flood stages. 

b. Adequate protection works, such as grouted rip-rap, gabions, etc., extending 10 meters on both sides of the outlet structure shall be provided to protect the structure from scouring. 

c. Rivers/creeks that are recipient of storm runoff from drainage outlets of subdivisions must be checked as regards their capacity to contain the flood waters without overbanking and should be improved, when necessary, to prevent flooding in the adjoining areas. 

d. Drainage outlets of subdivisions may be allowed to discharge directly into existing drainage mains or laterals provided that these drainage mains or laterals provided that these drainage mains or laterals can safely absorb the storm runoff coming from the subdivision without causing back flow, flooding and damage to the structure and to life and property 

e. Drainage outlets discharging into rivers/creeks and existing drainage mains or laterals should be designed to discharge downstream and with a maximum skew angle of 30 degrees with the direction of flow in the channel. 

           Open canal that will be used to convey storm runoff from drainage outlets of subdivisions to the nearest rivers/creeks, lakes and other natural bodies of water shall be designed with an appropriate size and shape to carry the designed discharge with a minimum free board of 0.60 m and a bed slope that will neither cause silting nor scouring in the channel.  When necessary, the channel should be lined with grouted riprap or sodding for protection against scouring/erosion. 
 

F. DESIGN STANDARDS 
 

Chapter 7       
ANALYSIS AND RECOMMENDATIONS 

 Being Asia’s 18th Most Livable City and the country’s Number 1, the City of Davao continues its sustained efforts to bring about economic growth and development, as well as providing social services and essential infrastructure facilities.  Its government strives to initiate sound policies and programs for their environmental endeavors blended with the infrastructural projects.  However, despite the efforts, the City is still challenged and threatened by a number of local concerns that necessitate immediate but sustainable response. 

 The City’s tourism industry had created a tremendous investment brought by the influx of foreign and local tourists, conventions, and other functions for the past years.  For now, the City is still an image of everyone’s paradise.  But years in counting, if the problem on drainage and flood remains to be a part of the day to day life of every person entering the threshold of Davao, the image that used to be so picture perfect would soon be a horrifying and harsh reality.  Hence, an adaptive and sustainable drainage plan and flood-preventing infrastructures are some of today’s most urgent needs for the city. 

 Given the existence of two master plans, the 1982 Urban Drainage Master Plan and the Proposed 1998 Drainage Master Plan, the group undertook to come up with the following analysis and recommendations: 
 

ANALYSIS 

 The problem on drainage and flood is intricate and complex, given the engineering requirements and the need to protect life and property of the people in flood affected areas.  It becomes more difficult in a situation like that of Davao City where there is no enough space to develop an integrated drainage facilities specially in highly urban areas. 

In 1996, the Office of the City Planning and Development Council (OCPDC) identified some 26 priority drainage projects to alleviate the flooding in the low-lying areas in the city.  After a major constructions under the Regional Cities Project in the 1980s to early 1990s, these sites continue to suffer inundation during storm periods. Hence, the following assessments: 

1. Flood usually occurs during heavy downpours of rain.  Though natural causes such as heavy storm and rain can be beyond human control, there can still be ways to prevent its disastrous effects through some engineering and mechanical works. 
2. The overflowing of the Talomo River being a major drain of a lot of tributaries and creeks from the upstreams such as the Wangan Creek, Tagakpan Creek, Tamogan River, Pangan Grande, Gumalang Creek and Suawan River causes severe overflowing from the drain canals despite the absence of rain in the low lands.  This is further intensified by the inadequate drainage facilities in the area surrounding the Talomo River which finds its exit in the Davao Gulf. 
3. The demand of a wider and deeper canal drains and lateral drains along the major thoroughfares of  the Poblacion and other urbanized zones increases while the drainage canals remain to be in its size fit for the drainage needs 20 years ago.  The sizes of the drainage canals are insufficient to hold storm water aside from the water and liquid wastes discharged from the nearby business establishments and residential zones.  The fast paced development of the city requires an up to date drainage facilities which must suit the changing needs of time. 
4. Zone developments and other major constructions have been increasing.  Majority of this constructions have encroached in the city’s proposed alignment of the different drainage canals to catch the water flow which will altogether be drained in the main drains exiting to the Davao Gulf.  Because of failure to consider the water ways in issuing business permits, the clearing and relocation of right of ways will likely cause delay and difficulty in the construction of the drainage channels. (Case of Fortune Executive Homes) 
5. There appears to be no plotting and mapping of the city’s natural water ways to be used as basis in constructing the drainage canals and which subdivision developers could use as reference in directing the subdivision drainage to a natural catchment area.  Though the requirement in developing housing units demand that the drainage must flow to natural water ways, the developers on their end have a difficulty in establishing and locating natural water ways in their respective areas due to lack of  data of land mapping with emphasis on water ways  from the city government. 
6. Particularly in the Poblacion area, there is inadequate number of street inlets and manholes for the underground drain system.  This is the primary cause of temporary water ponding whenever a significant rainfall downpours occur. 
7. In the open lined canals, there is a prevalent haphazard construction of cross drains particularly on driveways, causing major constrictions on the stormwater flow due to undersized openings. 
8. Human Influence.  Uncollected garbage mostly consisting of non-degradable plastic sheets and other solid wastes is disposed into the open canal drains.  Most often, this is the cause of major clogging at constricted sections of the drain channel. 
9. There appears to be no sustained maintenance of existing storm drains.  These are extensive weed growth on most unlined canals.  Many concrete covers to street inlets and manholes are broken 
10. The lack of housing in close proximity to centers of employment in the urban area had forced erection dwellings over the major canals and the mushrooming of shanties in the waterways and riverbanks.  These settlements encroaching on the waterways are hazards to health, life and property. 
11. The 1998 proposed Master Plan has not yet been adopted by the city.  Therefore, it remains a proposal waiting for action.  In effect, the city has no concrete long-range Storm Drainage Master Plan.  The existing 1982 Master Plan appears to be inadequate and ineffective to respond to the present day flood problems since their engineering layouts are not appropriate for today.  Their basins and channels are small enough o contain rainwater. In addition, the 1982 Drainage Plan covers only the Poblacion area while the development trend today extends far north and far south. 
12. Solving the problem on flood and drainage requires a tremendous amount of political will.  For now, the proposed drainage plan needs a large budget for implementation.  The question goes back to the administration if ways can be ascertained to actualize the proposal before its too late to have a drainage plan. 

RECOMMENDATIONS

 Policy Directions 
In terms of policy directions, it is crucial that future developments be controlled so as not to disturb the natural balance of the environment.  The benefits from development and the impact on the environment should be weighed against each other in considering the feasibility of such development. 

It is equally important to establish the development capability of an area in considering its future land use. Existing laws regarding development along riverbanks, like the required easement, should likewise be strictly implemented. 

 The requirements in issuing permits and licenses intended to safeguard the environment must be faithfully pursued. 

 Similarly, the 1998 proposed Master Plan promises a more effective and sustainable drainage system because it aims to integrate different channels with expanded width and depth to accommodate stormwater and waterwastes.  It is a measure that hope to lessen if not eradicate the flood problem because the design is based on the foresight of development in the surrounding areas both industrial and residential growth.  This is indeed a priority measure. 

Change in Men 
 No matter how grand a drainage plan would be without the support and cooperation of local residents and entrepreneurs, the problem with flood will be an eternal disaster for us.  It  is undeniable that the constrictions in our drainage canals are due to the uncollected garbage, most of them plastic materials, coming from the people residing near these canals. 

 If man fails to realize this reality.  It would be a more difficult task ahead of our local leaders. 
 

Chapter 8
CONCLUSION 

The first drainage plan of Davao City was implemented in 1982.  Nonetheless, due to the inability of this plan to adapt to the rapid development, the local government of Davao decided to commission the DCCD Engineering Corporation to conduct a study on the drainage system.  This study and the recommendations thereof would eventually be adapted as an updated Master Drainage Plan of Davao City. 

The firm thus came up with the proposed Master Plan in 1998 under the Administration of former Mayor Rodrigo Duterte right before he was replaced by the Honorable Benjamin de Guzman as mayor of the city.  This plan, however, was not approved nor implemented due to two important factors.  First, the lack of necessary funds for the purpose of implementing the proposed Master Plan.  The construction cost amounted to a grand total of 397.597 million pesos.  Such an amount was to be loaned from either the World Bank or the Asian Development Bank.  However, such funding would be difficult for the city government to repay as it would entail interest rates that would be too high to defray.  Second, due to numerous other infrastructure and development projects, the drainage plan has been set aside for the moment.  Hence, the proposed comprehensive plan of the DCCD Engineering Corporation was never put into effect.  As a result, local HLURB officers are of the opinion that the passage of a number of years since the proposed plan was submitted has made it somewhat outmoded, making a need for a newer, more up-to-date model. 

 As a consequence of the lack of a Master Drainage Plan which could adapt to the present developments, Davao City is experiencing numerous floods.  The core of this problem lies in the fact that there is no coordination among the different drainage plans of various areas.  Applications for constructions and/or development of subdivisions have been approved without a foresight of the consequences which would ensue therefrom.  As differentiated from the country of Japan, Davao City has not adopted a coherent and integrated drainage plan which would work despite the changing times.  The plans in Davao City, have at the most, been for the present only.  It leaves much to say still for the  future. . .