Modeling the Effect of Different Forest Types on Water Balance in the Three Gorges Reservoir Area in China, with CoupModel

Round 1

Reviewer 1 Report

The manuspcript describes an interesting study about the surface water balance in the Three Gorges Resevoir in China, in an area characterized by three of plots with different types of canopy.  It uses the CoupModel to estimate all the different terms of the water balance, from evapotranspiration to  groundwater percolation, calibrating the model with the aid of precipitation, soil moiture and throughfall measurements on site, as well as some laboratory characterizations of the soil hydraulic conductivity.   The paper is clear, well written and thorougly conceived, with proper  methodology, discussion and conclusions.

I can recommend the publication of the manuscript as it is, neverheless i will give a suggestion for possible little improvements, letting the authors to decide about.

 

1) A topographic map of the site, with the indication of its location, the plots and canopies and the position of the meteorological station would be nice, although not strictly necessary.

2) The addition of the variables caption in table 4 would be useful too, although they are clearly mentioned in the above text.

3) Please control table 1 heading: it could be out of alignment

Author Response

Thank you for your patience. Please see the attachment for details.

Reviewer 2 Report

The current manuscript investigated the effect of afforestation on various hydrological and water balance parameters. To do so the authors selected three regions of different vegetation: i) oak (Lithocarpus glaber) forestland, ii) Chinese fir (Cunninghamia lanceolata) forestland and iii) maize (Zea mays) farmland and performed experimental measurements on several parameters including precipitation, throughfall, stemflow, vegetation and weather conditions. Then they used the CoupModel to simulate and fit the experimental data gathered and estimated other parameters like interception, transpiration, evaporation and water soil recharge. The model successfully fitted the measured data and the authors concluded that i) a change in land use from cropland to forest may negatively impact the ground water recharge, ii) the vegetation type of afforestation can significantly influence the magnitude of water balance components.

The current work is interesting and can be published in Water because it includes experiments conducted on real test cases and the author’s conclusions may impact the quality of drinkable water. Although there are some issues that need to be addressed and a minor revision is advised.

• Table 1: Be specific about the coverage ratio. For example about Chinese Fir case what is the rest of 75% that is not covered? Is it empty land or maybe, is it low vegetation?
• Lines 140-146: Specify how many different locations were used to measure the soil moisture content. No care was taken to account for the possible spatial variability of this parameter? How this location was selected? Normally several locations would be used to calculate a realistic average. 
• Equation 1: It is suggested to add a term (i.e. “TR”) that represents man made alterations of the water balance in the system. This parameter should be explicitly set to zero to indicate that no system was modified externally by human intervention (i.e. drilling wells and so on).
• Line 216: Please elaborate why capillary rise and lateral runoff were disregarded?
• Line 241: “These indices…. equ”. Correct the typo “equ”= “equation”.
• Line 331-333: “He [40]…. Value of 35.8%.” Please use proper past tense, replace “find” with “found” and “report” with “reported”.
• Lines 349-350: “During this period…. greater than precipitation”. Please elaborate how evapotranspiration may be higher than precipitation? Is it because trees access stored water in soil or in underground aquifers, with their root system?
• Lines 433-436: “For example… farmland (274 mm)”. Rephrase, the meaning here is not clear.

 

Author Response

Thank you for your patience. Please see the attachment for details.

Author Response File: Author Response.pdf