Abstract:

The CoupModel is a one-dimensional soil-vegetation-atmosphere transfer model (SVAT). It was applied to simulate and study the processes of soil moisture loss and gain in potato farmland, acacia woodland, and grassland occurring in the hill-gully region of the Loess Plateau of China. The objective of the study was to develop theoretical guidance for farmland management and restoration of sloping farmland to woodland using measured and simulated soil moisture dynamics in three different vegetation regimes. Simulations followed the expected pattern in which water storage within the soil reservoir decreased with increasing soil matric suction and soil-water reservoir capacities were all characterized by power functions. The farmland, acacia woodland, and grassland soils respectively received a water input of 437, 361 and 429 mm water accounting for 94.3%, 77.9% and 92.6% of total precipitation (463 mm) in the experimental period from June 2006 to May 2007. Water storage within the soil profile of 600 cm layers ranged between 72.8%-79.3%, 37.1%-41.2% and 41.4%-47.5% of the field capacity, respectively, in the farmland, acacia woodland and grassland. The total water loss from the soil reservoir over the simulation-year was 421, 393 and 468 mm, respectively. Overall, there was a net annual water gain of 15.3 mm in the farmland while there was a net annual water loss of 32 and 39 mm respectively from the acacia woodland and grassland. It was suggested that there was excess water for farmland to consume, while a water deficit occurred in the acacia woodland and grassland. Therefore, more attention should be paid on the assessment of sustainability of vegetation restoration with woodland and grassland species for improving soil water management and soil reservoir restoration.

Key words: CoupModel, soil reservoir, soil water, simulation, hill-gully region of the Loess Plateau of China