Application of Diurnal Soil Water Dynamics in Determining Effective Precipitation
Located in western Inner Mongolia, the Badain Jaran Desert is the second largest desert in China and consists of a regular series of stable megadunes, among which over 70 permanent lakes exist. The unexpected lakes in desert attracted research interests i
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Application of Diurnal Soil Water Dynamics in Determining Effective Precipitation
3.1 Introduction Infiltration has long been regarded as one of the most important problems for hydrological forecasting, due to its relevance to runoff, soil moisture storage, evapotranspiration, groundwater recharge and unsaturated flow [12, 24, 32]. Its significance on assessing the hydrological process, which is the main plant community shaping process, is even magnified in the arid ecosystems. In deserts, precipitation is often the sole source of water replenishment, while infiltration is the main process to understand how much rainfall could be retained in sand for some time before being either passed downward as percolation or returned to the atmosphere by evapotranspiration. One of the main hydrological issues in water scarce regions is to demonstrate whether modern rainfall is recharging aquifers through infiltration and on what rate or scale. The Badain Jaran Desert with unexpected numerous groundwater-fed perennial lakes has attracted substantial research interest in investigating the desert hydrological process, and the infiltration in this special landscape, with lakes among inter-dune areas [14, 36], has been widely studied. Hofmann [15, 16] stated there was an aquifer in the northern areas of the eastern lakes region, recharged directly by precipitation through infiltration process, while he did not study the infiltration rate. Based on hydrochemical and isotopic analysis, Gu et al. [14] pointed out that groundwater flowed from adjacent areas in the south to the north western part with a historic and fossil recharge (1,000–30,000 BP); and with the actual analytical results on groundwater chlorides, he estimated that 1–1.5 mm/yr
This chapter is based: Zeng, Y., Z. Su, L. Wan, Z. Yang, T. Zhang, H. Tian, X. Shi, X. Wang, and W. Cao, (2009), Diurnal pattern of the drying front in desert and its application for determining the effective infiltration, Hydrol. Earth Syst. Sci., 13: 703–714.
Y. Zeng, Coupled Dynamics in Soil, Springer Theses, DOI: 10.1007/978-3-642-34073-4_3, Ó Springer-Verlag Berlin Heidelberg 2013
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Application of Diurnal Soil Water Dynamics
of groundwater recharge would occur by direct infiltration from precipitation. With tracer methods, more and more recharge rate data were reported and added to a growing catalogue of tracer results for the Badain Jaran Desert region, which led estimates of the average recharge rate in this region vary from 0.95 to 3.6 mm yr-1 [3, 7–9, 11, 15, 18, 21, 22, 43, 44, 49]. Aforementioned studies were mainly focused on the rate at which the infiltrated rainfall recharged the groundwater, which could be called the effective infiltration or the effective rainfall [1, 41]. However, the effective infiltration or rainfall can also be defined as the amount of rainfall stored in the shrub root zone, excluding the fraction that runs off the soil surface or passes through the root zone that does not contribute to shrub growth and the fraction that evaporates [39]. From abo
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