By Boy Tunnel

For the last century or so, geomorphologists have been studying the land forms on our Earth and the processes that form them. For many, the study of badlands has been the one of the most tasking or at least one of the most intriguing. Badlands are land forms characteristic of semiarid regions where erosion rates dominate. The article by A. Calvo-Cases and A.M. Harvey sets to examine the processes that contribute to the development and evolution of badlands. The article investigates these processes on both a short term scale of one year and on a ten-year span. In general, the article looks at climatic change as the ultimate contributing factor in badlands development. It states that the climatic change can contribute either to increased erosion or to badlands surface durability.

In the article, the authors are sure to describe the appearances and characteristics of the four badlands sites which were studied. Aspects such as approximate local relief levels and sources of badlands formation and their time frames are presented. As well, climatic conditions such as annual precipitation levels and average temperature levels are considered before the observations are made. Mineralogical composition and vegetation cover levels are said to have an impact on the development of the badlands in the various regions. The above characteristics all have an effect on the morphological features of the badlands. For instance, processes such as rilling, piping, swelling, overland flow and mass wasting are all affected by characteristics such as precipitation and vegetation levels. To monitor visual changes, the researchers used photographs so that crack patterns, surface roughness and rill networks could be examined and compared. At the first study region, Tabernas, there was little change in the rill networks except for some small disappearances of rills and the formation of a few new ones. There was little response to rainfall by the rill patterns and similarly, the few changes in crack density and surface roughness indicate a low rate of swelling. One point that was noted at this particular site was that there were sediment deposit fluctuations as a result of high erosion rates.

At region number two, name Vera, two complete destruction and regeneration episodes of the rill networks took place. The researchers here established that rill generation is associated with more humidity and rill destruction with drier weather. It was also assumed that the heavy rains brought about a more dense rill network, mud flows, and a removal or surface materials. Consequently, further rains were found to form new rill networks.

At Petrer, the third region, the most notable changes occur in surface roughness and crack and rill characteristics as a direct response to precipitation levels. There is little roughness when there is moisture and the rills become more dense as heavy rains occur.

At the fourth region, Monnegre, the main factor affecting badlands development is the down-cutting of the main gullies. This is related to higher erosion and swelling rates in the summer months.

The results of this research leave some very clear, simple conclusions about what factors contribute to the development of badlands formations. For example, climatic conditions have an enormous effect on badlands evolution as frequent rains contribute to rill development while dry periods staggered by rare heavy rains increase rill destruction, cracking, and mass movement. Also, the mineral composition of the badlands formation seems to have a significant effect on the vulnerability of the formation to erosion. Furthermore, the surface form of the badlands formation can determine whether or not new rill systems can form easily. For example, sites with thin regolith cover show few changes. All in all, the results of the research indicated that certain climatic and material conditions have the greatest effect on badlands evolution.

The research data in this article is valid and believable mainly due to the well-balanced, fair approach taken by the researchers. For instance, the research was conducted in a variety of regions, each with characteristics which differed and some which were similar to those of the other regions. Also, the various settings allowed the researchers to study different situations. The methods used to collect the data, such as the use of photographs, were practical and effective while the figures and charts presented were useful and detailed. Furthermore, the results of the research were fairly obtained and displayed. The conclusions which could be reached by the research were realistic and made common sense. All in all, the article is believable and the conclusions drawn from it are valid and simple.

Calvo-Cases, A. and A.M. Harvey. "Morphology and Development of Selected Badlands in Southeast Spain: Implications of Climatic Changes". In Earth Surface Processes and Landforms. Vol. 21, 725-735. 1996.