Abstract
AbstractUnderstanding the dynamics of salt movement in the soil is a prerequisite for devising appropriate management strategies for land productivity of coastal regions, especially low‐lying delta regions, which support many millions of farmers around the world. At present, there are no numerical models able to resolve soil salinity at regional scale and at daily time steps. In this research, we develop a novel holistic approach to simulate soil salinization comprising an emulator‐based soil salt and water balance calculated at daily time steps. The method is demonstrated for the agriculture areas of coastal Bangladesh (∼20,000 km2). This shows that we can reproduce the dynamics of soil salinity under multiple land uses, including rice crops, combined shrimp and rice farming, as well as non‐rice crops. The model also reproduced well the observed spatial soil salinity for the year 2009. Using this approach, we have projected the soil salinity for three different climate ensembles, including relative sea‐level rise for the year 2050. Projected soil salinity changes are significantly smaller than other reported projections. The results suggest that inter‐season weather variability is a key driver of salinization of agriculture soils at coastal Bangladesh.
Highlights
The coastal zone comprises only 3% of the earth’s surface and accommodate 60% of the world’s population, a figure set to increase to 80% by 2050 [Hyun et al, 2009]
About 600 million people currently inhabit low-elevation coastal zones that will be affected by progressive salinization [Dasgupta et al, 2015]
We have developed a system dynamic model structure that integrate for first time the key drivers of soil salinity in low lying deltas illustrated in Figure 1 a regional scale
Summary
The coastal zone comprises only 3% of the earth’s surface and accommodate 60% of the world’s population, a figure set to increase to 80% by 2050 [Hyun et al, 2009]. Soil salinity is a major, and the most persistent, threat to irrigated agriculture many deltas, such as in coastal Bangladesh [D. Crop growth is hampered by salt accumulation in the crop root zone. Salt in the soil interferes with the crop growth when its concentration exceeds the tolerance limits of the crop [Ayers and Westcot, 1985; Rhoades and Merrill, 1975]. Plant growth is restricted even though enough water may be present in the root zone, because salt reduces the plant’s ability to take up water and can be toxic to the plant. In Bangladesh, >30% of the net cultivable land is in the coastal area. Of the 1.689 Mha of coastal lands, about 1.056 Mha are adversely affected by varying degrees of soil salinity [SRDI, 2010]. The agricultural sector of Bangladesh constitutes an important component of the national economy accounting for around 21% of the national
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