the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 29 Nov 2024
Hydrological drivers of groundwater recharge changes under different emission scenarios in agricultural lands
Abstract. Groundwater is a crucial resource that helps ensure the security of food and water. Although the earth's water resources are being negatively impacted by climate change in every manner, there is still limited research on predicting future groundwater recharge. This study constructed the Soil and Water Assessment Tool (SWAT) under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) in conjunction with two General Circulation Models (GCMs) from Coupled Model Intercomparison Project 6 (CMIP6) to predict the change in agriculture groundwater recharge in 2021–2045 relative to the baseline historical data. The Yang River Basin in Hebei Province, China, which is mainly covered by agricultural land along the basin, as the study area to understand how climate change drives groundwater recharge in agricultural land. The results show that the model performs well, with Nash-Sutcliffe Efficiency (NSE) of 0.82 and 0.76 in the validation and calibration periods, respectively. The expected temperature and precipitation have increased more, 16.1 %–31.3 % and 1.8 °C–2.5 °C, respectively, compared with the historical period 1981–2005.While evapotranspiration (ET) has increased, the distribution of agricultural groundwater recharge reflected spatially varying characteristics, with an overall increasing trend of 31.3 % (2021–2045). Consequently, the study area was divided into five regions with varying degrees of wetness and dryness based on the spatial distribution of precipitation (P). It was found that in the higher–precipitation regions, runoff contributed a portion of the future net atmospheric input (P-ET), and it was further concluded that precipitation was the primary climatic factor that drove the recharge to farmland, while evapotranspiration also had an impact on the change in recharge for the relatively dry regions. This will help the region achieve sustainable development and get ready for climate change in the future. It will also provide local policy makers with some knowledge.
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CC1: 'Comment on egusphere-2024-3186', Nima Zafarmomen, 13 Dec 2024
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- How does this paper contribute new insights to the understanding of groundwater recharge under climate change compared to previous studies?
- Are the conclusions sufficiently supported by the data and analysis?
- How does the model account for the spatial variability in recharge trends, especially in regions with contrasting precipitation and ET patterns?
- Are the relationships between precipitation, ET, and recharge sufficiently explored for all sub-regions?
- Could the study include an analysis of the impacts of future land use changes or irrigation practices?
- What role might alternative hydrological models or multi-model ensembles play in validating the results?
- I strongly recommend that the authors consider discussing the SWAT-MODFLOW model as part of the methodology or in the discussion section. SWAT-MODFLOW is a widely used integrated modeling tool that couples surface water and groundwater simulations, providing a comprehensive approach to assessing hydrological processes. I highly recommend cite below papers:
Quantifying the effects of climate change on hydrological regime and stream biota in a groundwater-dominated catchment: A modelling approach combining SWAT-MODFLOW with flow-biota empirical models
Assimilation of Sentinel‐Based Leaf Area Index for Modeling Surface‐Ground Water Interactions in Irrigation Districts
Comparison of abstraction scenarios simulated by SWAT and SWAT-MODFLOW
Citation: https://doi.org/10.5194/egusphere-2024-3186-CC1 -
RC1: 'Comment on egusphere-2024-3186', Anonymous Referee #1, 17 Dec 2024
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This is a carefully done study and the findings are of considerable interest. And the submission is worth of publication. Following are some minor comments:
- In this paper, the Yang River Basin, a predominantly farmland area in Hebei Province, China, was selected as a study area in this study to understand how climate change drives groundwater recharge in farmland. In section 2.1 of the article, it is mentioned that groundwater recharge from agricultural land accounts for 90 % of the total groundwater recharge, but the entire area of agricultural land accounts for 36 % of the total groundwater recharge. It is questioned whether the 90% groundwater recharge is too much.
- In the introduction of the paper Figure 1 illustrates the interaction of groundwater systems with agricultural recharge in the face of climate change, and the numerous processes that partially affect groundwater systems. In the text there should be some indication of a more detailed description of this figure .
- To investigate the factors driving groundwater recharge in agricultural fields, the entire study area was split into five sections, WP1–WP5, based on the spatial distribution of precipitation (Fig. 3d), with WP5 having the highest precipitation. There is too little description of the five subregions in the text, which could be differentiated by simply describing the individual precipitation as well as climatic conditions such as temperature in each of the five subregions. Can be described in tables.
- Section 2.2.1 of the article, which establishes a database of soil properties for the SWAT model, Table 1 illustrates the Soil types and related parameter. There are some abbreviations in the table. I recommend that the authors define all abbreviations clearly.
- Section 2.2.2 of the article, which analyses of nine parameters in the SWAT model to improve the accuracy of the results. I suggest to define and explain in detail the moral meaning of these 9 parameters.
- Section 3.1 of the article about the NSE and were used to validate the model, but there is only one in the results section, so it is recommended to complete it.
- Based on the water balance elements, the Pearson correlation coefficients are used to calculate the strong and weak links between precipitation, temperature, snow, ET, soil water, runoff, and recharge, and Figure 16 illustrates how variations in recharge have a significant positive correlation with precipitation and runoff under SSP5-8.5 scenario. It is suggested that additional information be provided on what hydrological factors are associated with recharge under the other scenario (SSP2-4.5) with lower rainfall and higher temperatures.
- While this article examines and predicts the climatic and hydrological factors that drive groundwater recharge on farmland under climate change, I suggest that further consideration could be given to differences in recharge across crops and the factors that influence recharge.
- The number of references in the article is a bit low, it is recommended to increase the number of citations.
- Regarding the two climate models (GFDL-CM4 and MRI-ESM2-0) selected for the article, what is the rationale for their selection, and if possible, I would suggest a brief description of the rationale for the selection of these two GCM models.
- In addition, the list of reference is not in our style. It is close but not completely correct. Please attached a PDF file with ‘Instruction for Authors’ which shows examples.
- It is noted that the manuscript needs careful editing by someone with expertise in technical English editing paying particular attention to English grammar and sentence structure so that the results of this study are clear to the readers.
- Add more description of Figure 1. Figure 1 shows the Interaction of groundwater systems with agricultural recharge under the influence of climate change and the numerous processes that partially affect groundwater systems. I suggest a brief explanation of a few important parts of the diagram that are in some way related to groundwater recharge.
Citation: https://doi.org/10.5194/egusphere-2024-3186-RC1
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