Environmental consequences of dam construction: a case study from Saudi Arabia

The objective of this study was to assess the variation in the vegetation cover as a result of the construction of Wadi Baish Dam, Saudi Arabia by the remote sensing techniques and geographic information system. The variations in soil physical and chemical properties as well as irrigation water quality were also investigated. The results show that the soil morphological, physical, and chemical characteristics were affected by dam construction. The data reveal that area under the green cover in Wadi Baish declined from 23.7 km(2) in 2005 to 13.3 km(2) in 2013 before and after the construction of Baish Dam, respectively. Moreover, soil salinity level (ECe) and the sodium adsorption ratio (SAR) were increased following the dam construction. In addition, soil texture, soil organic matter content, and soil macro-(P and K) and micro-(Fe, Mn, Zn, and Cu) nutrient availability were changed after dam construction. In the surface layer of soil, the clay content decreased from 156-211 ( before the dam construction) to 56-106 g kg(-1) (after the dam construction). However, the sand content increased from 279-344 to 869-944 g kg(-1) before and after dam construction, respectively. The soil organic matter content decreased from 6.8-11.0 to 0.5-7.2 g kg(-1). It was concluded that the dam construction raised the salinity level in soil and underground water level and thus caused negative environmental and agricultural changes. A proper management is necessary after dam construction to improve soil fertility and prevent soil and water from salinization in Wadi Baish, Saudi Arabia.