Mahmoud Shereif H, Alazba A A
Alamoudi Water Research Chair, King Saud University, PO Box: 2460, 11451, Riyadh, Saudi Arabia.
PLoS One. 2015 Apr 29;10(4):e0125805. doi: 10.1371/journal.pone.0125805. eCollection 2015.
The hydrological response to land cover changes induced by human activities in arid regions has attracted increased research interest in recent decades. The study reported herein assessed the spatial and quantitative changes in surface runoff resulting from land cover change in the Al-Baha region of Saudi Arabia between 1990 and 2000 using an ArcGIS-surface runoff model and predicted land cover and surface runoff depth in 2030 using Markov chain analysis. Land cover maps for 1990 and 2000 were derived from satellite images using ArcGIS 10.1. The findings reveal a 26% decrease in forest and shrubland area, 28% increase in irrigated cropland, 1.5% increase in sparsely vegetated land and 0.5% increase in bare soil between 1990 and 2000. Overall, land cover changes resulted in a significant decrease in runoff depth values in most of the region. The decrease in surface runoff depth ranged from 25-106 mm/year in a 7020-km2 area, whereas the increase in such depth reached only 10 mm/year in a 243-km2 area. A maximum increase of 73 mm/year was seen in a limited area. The surface runoff depth decreased to the greatest extent in the central region of the study area due to the huge transition in land cover classes associated with the construction of 25 rainwater harvesting dams. The land cover prediction revealed a greater than twofold increase in irrigated cropland during the 2000-2030 period, whereas forest and shrubland are anticipated to occupy just 225 km2 of land area by 2030, a significant decrease from the 747 km2 they occupied in 2000. Overall, changes in land cover are predicted to result in an annual increase in irrigated cropland and dramatic decline in forest area in the study area over the next few decades. The increase in surface runoff depth is likely to have significant implications for irrigation activities.
近几十年来，干旱地区人类活动引起的土地覆盖变化所产生的水文响应吸引了越来越多的研究兴趣。本文报道的研究使用ArcGIS地表径流模型评估了1990年至2000年沙特阿拉伯巴哈地区土地覆盖变化导致的地表径流的空间和定量变化，并使用马尔可夫链分析预测了2030年的土地覆盖和地表径流深度。1990年和2000年的土地覆盖图是使用ArcGIS 10.1从卫星图像中获取的。研究结果显示，1990年至2000年期间，森林和灌木林面积减少了26%，灌溉农田面积增加了28%，植被稀疏土地面积增加了1.5%，裸土面积增加了0.5%。总体而言，土地覆盖变化导致该地区大部分地区的径流深度值显著下降。在一个7020平方公里的区域内，地表径流深度下降幅度为每年25 - 106毫米，而在一个243平方公里的区域内，地表径流深度仅增加了每年10毫米。在一个有限的区域内，地表径流深度最大增加了73毫米/年。由于与25座雨水收集坝建设相关的土地覆盖类别发生了巨大转变，研究区域中部的地表径流深度下降幅度最大。土地覆盖预测显示，在2000 - 2030年期间，灌溉农田面积将增加两倍多，而到2030年，森林和灌木林预计仅占225平方公里的土地面积，与2000年占据的747平方公里相比大幅减少。总体而言，预计未来几十年研究区域内的土地覆盖变化将导致灌溉农田面积每年增加，森林面积急剧下降。地表径流深度的增加可能会对灌溉活动产生重大影响。
