Spatial analysis of water conservation function in northeast China under different climatic conditions

Northeast China is one of the important ecological functional areas in China. There are several types of ecosystems in the region and each has its unique water conservation function. Ecosystems are known to play a significant role in flood control and disaster reduction, as well as provide ecological and human settlement security. Previous studies on water conservation function have depended mainly on different hydrological models with varying temporal scales; however, few studies have investigated the spatial distribution of water conservation function under different climatic conditions. In the present study, a standardized precipitation evaporation index(SPEI) was used to select the typical climate years(dry, normal, and wet) for the study area. The water conservation function under different climatic conditions was analyzed based on the water balance method, the SCS-CN model, and the Penman-Monteith equation. The results indicated that the total amount of water conservation in the growing seasons varied significantly under different climatic conditions in northeast China. They were 221.464, 323.149, and 396.933 billion m~3 in the dry(SPEI=-1.26), normal(SPEI=-0.22), and wet year(SPEI=1.05), respectively. The Changbai mountain area had the highest water conservation function, followed by the Daxing′an and Xiaoxing′an Mountain areas. The lowest water conservation quantity was distributed mainly in the pasture area in the west of Hulunbuir. Some areas of the Northeast Plain also had low water conservation such as Baicheng, Tongliao, and Jixi. Moreover, the areas of farmland plain, located in the middle, south, and east of northeast China such as most areas of Songnen, Liaohe, and Sanjiang plains had moderate water conservation function. Both climatic conditions and land-use types affected the extent of water conservation. The total amount of water conservation followed the order of forest > cropland > grassland > wetland. In dry and normal years, land use dramatically affected the average water conservation capacity per area in the order of forest > cropland > wetland > grassland. In contrast, the order of the value for wet years is forest > wetland > farmland > grassland. These results reveal the quantity, spatial distribution, and main driving factors for water conservation in important ecosystems under three typical climates in the northeast of China. This provides scientific guidance for regional ecological space planning and ecosystem management.