Human-Induced Alterations to Land Use and Climate and Their Responses for Hydrology and Water Management in the Mekong River Basin

Abstract

The Mekong River Basin (MRB) is one of the significant river basins in the world. For political and economic reasons, it has remained mostly in its natural condition. However, with population increases and rapid industrial growth in the Mekong region, the river has recently become a hotbed of hydropower development projects. This study evaluated these changing hydrological conditions, primarily driven by climate as well as land use and land cover change between 1992 and 2015 and into the future. A 3% increase in croplands and a 1–2% decrease in grasslands, shrublands, and forests was evident in the basin. Similarly, an increase in temperature of 1–6 °C and in precipitation of 15% was projected for 2015–2099. These natural and climate-induced changes were incorporated into two hydrological models to evaluate impacts on water budget components, particularly streamflow. Wet season flows increased by up to 10%; no significant change in dry season flows under natural conditions was evident. Anomaly in streamflows due to climate change was present in the Chiang Saen and Luang Prabang, and the remaining flow stations showed up to a 5% increase. A coefficient of variation <1 suggested no major difference in flows between the pre- and post-development of hydropower projects. The results suggested an increasing trend in streamflow without the effect of dams, while the inclusion of a few major dams resulted in decreased river streamflow of 6% to 15% possibly due to irrigation diversions and climate change. However, these estimates fall within the range of uncertainties in natural climate variability and hydrological parameter estimations. This study offers insights into the relationship between biophysical and anthropogenic factors and highlights that management of the Mekong River is critical to optimally manage increased wet season flows and decreased dry season flows and handle irrigation diversions to meet the demand for food and energy production.

Precipitation and Flow Variations in the Lancang–Mekong River Basin and the Implications of Monsoon Fluctuation and Regional Topography

“…Excessive and intensive precipitation during the rainy season may induce a flood risk of different magnitudes, ranges and durations over the mainstream and various tributaries [2]. As the residents of the riparian countries are highly dependent on water resources to develop agriculture and inland fisheries, these uncertainties have important regional and socioeconomic impacts [12][13][14][15].…”

Analysis of Runoff Trends and Drivers in the Haihe River Basin, China

“…Climate change and human activities are two major factors that drive changes in the hydrological cycle [1,36]. Climate change includes changes in precipitation and air temperature caused by potential evapotranspiration fluctuations [15].…”

Exploring Empirical Linkage of Water Level–Climate–Vegetation across the Three Georges Dam Areas

“…Zhao used a double mass curve analysis to assess nature and anthropogenic influences on water discharge and sediment load in the Yangtze River [6]. Reservoir regulation played a significant role in modifying peak flows in the wet season and low flows in the dry season, and the irrigation activities in the cropped or vegetated area would affect the overall hydrology condition [7,8]. However, these statistical methods are often too simplistic to represent complex climate-vegetation causality due to linearity assumptions.…”