Estimating the Effect of Precipitation and Vegetation on Water Yield in Northern China

Abstract

The effect of vegetation on water yield is a popular and important issue in ecohydrological studies. In response to the widely observed degradation of formerly forested land and the rising demands for paper pulp, industrial wood, and wood fuel, the need for large-scale reforestation programs has been expressed repeatedly. To address the increasing levels of soil erosion and desertifi cation, China has implemented many large-scale reforestation programs in recent decades [1]. While creating many economic and ecological benefi ts, reforestation could also potentially reduce water capacity [2][3]. Because of this, correct understanding of the forest-water relationship is particularly important.There have been many infl uential studies made in understanding forest and water relationships during the past century around the globe. Our understanding of the forest impact on annual water yield is well advanced and there are robust methods available for predicting the impact of forest change on the mean annual water balance [4]. Methods have also been established that allow the prediction of water yield changes in response to forest change at the annual time scale [5][6].Although researchers concurred with that forests decrease water yield, the decreasing extent is different. Pol. J. Environ. Stud. Vol. 27, No. 1 (2018), 305-311 AbstractThis study attempts to analyze how precipitation and vegetation affect water yield in Haihe watershed. Based on the annual runoff and meteorological data, the water balance equation and the calibrated Zhang model were used to simulate the effects of precipitation and vegetation on water yield. The simulated results showed that the effect of precipitation on water yield was linear in mountainous area of Haihe watershed, and a 1 mm change (increase or decrease) in precipitation will cause a 0.51 mm change in water yield; under the mean annual precipitation of 534 mm, the effects of decreasing water yield by per unit cover ratio for forest, grassland, and farmland were 1.26, 0.47, and 0.69 mm, respectively. The decreased water yields for forest, grassland, and farmland were associated with aridity indexes by negative power functions, and indicate that the effect of vegetation on water yield was smaller in drier areas. For three vegetation types the effects of vegetation on water yield were similar for crops and grass, and were much larger for forest.

Effects of Landscape Pattern Change on Water Yield and Nonpoint Source Pollution in the Hun-Taizi River Watershed, China

“…At the class level, WYLD and nutrient yield were negatively correlated with the LPI and AI of forestland and positively correlated with the LPI and AI of dry farmland (Figure 9), which is consistent with results from related studies [4,41,51]. The annual evapotranspiration (ET) losses of crops are generally smaller than the ET losses from trees [51,52]. The change from forestland to farmland resulted in decreased ET, thereby increasing WYLD [34].…”

Research Progress on Identification of Basin Water Yield Baseline and Regulation Slope Water Yield Process

“…Nowadays, the research on runoff generation mechanisms is changing towards multiple spatiotemporal scales [24][25][26], and new demands are gradually emerging. The research perspective has also begun to move towards the basin water yield process, to explore the basin water yield, water yield coefficient, and ecosystem water yield service [27][28][29]. The primary goal of water yield baseline establishment is to enrich the natural capacity of the basin.…”