A Comprehensive Review of Specific Yield in Land Surface and Groundwater Studies

Specific yield is a key parameter for estimating water table depth in land surface models, which can strongly modulate the interaction between soil moisture and groundwater and further affect the water budget between the land surface and the atmosphere. The error in water table simulation comes mainly from the uncertainty in determining the specific yield. The determination of specific yield in land surface models is simplified, and a uniform empirical constant value of specific yield is generally used in global simulations, especially for deep aquifers, for its convenience. However, a uniform fixed value is insufficient for worldwide aquifers with diverse environments. Before estimating specific yields for global aquifers in Earth system simulations, a comprehensive understanding of the specific yield and comparison of current determination methods are required. This study provides a comprehensive review of the literature focusing on different concepts of the specific yield, complex variabilities, and various determination methods. Specifically, we detail the distinction and interconversion of different subconcepts that are used to reflect the influence of different factors on the specific yield and are likely to confuse scholars; present the representative comparisons of previous estimated specific yields using different methods, and summarize the applicabilities and limitations of these methods, indicating directions for their future improvement.

Automated summary

Specific yield is crucial for estimating water table depth in land surface models. The error in water table simulation mainly stems from the uncertainty in determining specific yield. While a uniform fixed value is commonly used in global simulations, it may not be sufficient for diverse aquifers worldwide.