Soil and aquifer salinization: toward an integrated approach for salinity management of groundwater

Degradation of the quality of groundwater due to salinization processes is one of the key issues limiting the global dependence on groundwater in aquifers. As the salinization of shallow aquifers is closely related to root-zone salinization, the two must be considered together. This chapter initially describes the physical and chemical processes causing salinization of the root-zone and shallow aquifers, highlighting the dynamics of these processes and how they can be influenced by irrigation and drainage practices, thus illustrating the connectivity between soil and groundwater salinization. The processes leading to aquifer salinization in both inland and coastal areas are discussed. The roles of extractive resource industries, such as mining and coal bed methane operations, in causing aquifer salinization are also outlined. Hydrogeochemical changes occurring during salinization of aquifers are examined with the aid of Piper and Mixing Diagrams. The chapter then illustrates the extent of the problem of groundwater salinization as influenced by management and policy using two case studies. The first is representative of a developing country and explores management of salt-affected soils in the Indus Valley, Pakistan, while the second looks at a developed country, and illustrates how through monitoring we can deducecauses of shallow aquifer salinity in the Namoi Catchment of NSW, Australia. Finally, there is a section on integration and conclusions where we illustrate how management to mitigate salinization needs to be integrated with policy to diminish the threat to productivity that occurs with groundwater degradation

Water use by a groundwater dependent maize in a semi-arid region of Inner Mongolia: evapotranspiration partitioning and capillary rise

tThis study aimed at assessing the soil water balance, groundwater contribution, crop transpiration andsoil evaporation of a rainfed maize crop in Horqin sandy area, north-eastern Inner Mongolia, China.Two years of field data from the Agula site were used, 2008 with relatively high rainfall (363 mm) andhigh water table, and 2009 with low rainfall (125 mm) and lower water table. The SIMDualKc waterbalance model was calibrated with observed soil water content data of 2008 and validated with dataof 2009. The model uses the dual crop coefficient approach for evapotranspiration (ET) partitioning,and parametric functions for computing capillary rise. The respective modelling results show that thegroundwater contribution represented ca. 50% of crop ET in both years. Estimation errors are small,with root mean square errors of 0.007 and 0.008 cm3cm−3respectively in 2008 and 2009. The Nash andSutcliffe modelling efficiency were high, 0.93 in both years, which indicates a low variance of residuals.The calibrated basal crop coefficient Kcb mid= 0.95 denotes a low density of the crop because it is muchlower than common potential values. Soil evaporation was relatively low, 23% of ET in the wet year and17% in the dry year, because capillary rise does not contribute to soil evaporation but to roots extractiononly. Results show that capillary rise plays a main role in supplying the vegetation throughout the season,hence a strong dependence of vegetation upon groundwater.info:eu-repo/semantics/publishedVersio