Integrated factor analysis of water level variation in geographically isolated ponds.

Small geographically isolated ponds provide a multitude of ecological functions and services, but water table fluctuations alter the magnitude of these services. Understanding temporal and spatial changes of surface water levels in the watershed, and their spatial variability, is critical for restoration and protection of small ponds. A biweight spatial consistency test was employed to quantify the seasonal variability of surface water tables for 50 ponds and hydrological connectivity models, and land use metrics, topographic characteristics, and irrigation needs, for groundwater, were introduced into the model to identify influencing factors. The spatial difference of water level changes in the rice season was greater than the wheat season while water table increased in the wheat season and declined in the rice season. Continuous runoff with complete surface hydrological connectivity of ponds, which was strongly related to precipitation, occurred only one time during the study period. Water level dynamics were largely uncorrelated to surface hydrological connectivity but were linked to watershed and pond size. By evaluating irrigation water requirements, irrigation was a primary human management factor affecting the water table changes in ponds. Groundwater also enriched influence factors that estimated water level variation in ponds, and these results will provide support for improved water resource management and ponds protection purposes.