Spatiotemporal dynamics and interrelationship between soil moisture and groundwater over the Critical Zone Observatory in the Central Ganga plain, North India
Abstract. The understanding of spatiotemporal dynamics of Earth’s hydrological components and their controls is critical for efficient water resource management, especially in the agriculture-dominated landscapes. In this study, we utilize the empirical orthogonal function (EOF), random combination, and temporal stability approach on the soil moisture (SM) and depth to groundwater table (DTGT) observations from the Critical Zone Observatory in the Ganga basin to understand their spatiotemporal variability and optimal sampling strategies. Around 91 % of the observed DTGT spatial variations are explained by the first two spatial EOF whereas the first five EOFs explain only 67 % of the total SM variability. Topography and soil texture (% clay) are considered to be the leading factors that drive the spatial pattern of both the attributes. Furthermore, we noted that four SM sampling locations and two monitoring well, selected randomly can capture the mean spatial variability with an accuracy of 3 % vol /vol and 0.90 mgbl (meter below ground level) respectively. Moreover, four temporally stable SM sites and a single observation well are identified, which provide the spatial mean with an absolute error of ±2 % vol /vol and 0.36 mgbl respectively. Overall, this study provides an insight to spatiotemporal hydrological controls in an intensively managed landscape and has important implications for water resource management in such regions.
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