Modeling Precipitation-runoff Relationships to Determine Water Yield from a Ponderosa Pine Forest Watershed

Résumé du livre

A stochastic precipitation-runoff modeling is used to estimate a cold and warm-seasons water yield from a ponderosa pine forested watershed in the north-central Arizona. The model consists of two parts namely, simulation of the temporal and spatial distribution of precipitation using a stochastic, event-based approach and estimation of water yield from the watershed using deterministic and spatially varied water balance technique. In the first part, a selected group of theoretical probability distribution functions are used to describe the probability distribution of the various precipitation characteristics, such as storm depth, storm duration, and interarrival time between events. Then, a synthetic data of each precipitation characteristic are generated using the best distribution function that fit the observed data. The other precipitation characteristics evaluated in this part is the spatial distribution of precipitation. The distribution of storm depth and duration across the watershed with respect to the landscape characteristics such as latitude, longitude, elevation and aspect is studied. In addition, the form of precipitation, snow or snow during the coldseason is analyzed by simulating temperature. Overall the models for two seasons work well except that the cold-season model overestimate precipitation events of small depth and duration while, the warm-season model overestimate the total seasonal amount.