## 3 Results
### Intream and Off-Stream EWRs
#### 3.2.2 Off-Stream EWRs and Their Impact Factors  
The off-stream EWRs in this study are derived from the RHESSys model as the sum of vegetation transpiration, interception evaporation, surface storage evaporation, litter storage evaporation and soil evaporation. At the monthly scale, the multi-year average off-stream EWRs range from 11 to 264 million m\({}^{3}\), peaking in July. For vegetation transpiration, active growth mainly occurs between April and October, with transpiration contributions exceeding 29%, and particularly high contributions in July, August and September (over 42% each), with a multi-year average transpiration proportion of 37.50% (Figure 8a). This indicates that analyses of the climate-vegetation-hydrology interactions in the Hailar River Basin should focus on the April-October timeframe. Figure 8: Inter- and intra-variation of off-stream EWRs and their response to monthly temperature and precipitation: (a) monthly contribution ratio of vegetation transpiration; (b) linear correlation between monthly precipitation and evapotranspiration; (c) temporal trends of precipitation, temperature and ET; (d–f) interannual variations of total evapotranspiration and vegetation transpiration under different scenarios. Figure 7: Response of monthly instream EWRs to temperature and precipitation. Figure 8b shows the linear correlation between monthly precipitation and evapotranspiration from 1982 to 2012, with an R\({}^{2}\) of 0.88 (\(p<0.01\)). No significant correlation is observed between monthly evapotranspiration and average monthly temperature. At the interannual scale, the trends of evapotranspiration with precipitation and temperature (RHESSys model outputs) from 1982 to 2012 reveal that evapotranspiration (slope: 1.09 mm/year) does not increase with rising temperature (slope: 0.02 C/year)--a phenomenon known as the \"evaporation paradox\". Instead, it declines in alignment with decreasing precipitation (slope: 3.14 mm/year), indicating that off-stream EWRs are primarily influenced by precipitation rather than temperature (Figure 8c). The interannual variation of total evapotranspiration and vegetation transpiration under the baseline, no-vegetation-dynamics, and no-lateral-flow-redistribution scenarios indicates that the multi-year average off-stream EWRs are 1140, 1117, and 1114 million m\({}^{3}\), respectively--slightly lower in the latter two scenarios but with minimal impact (Figure 8d-f). Under the no-vegetation-dynamics scenario, vegetation transpiration (313 million m\({}^{3}\)) is lower than in the baseline scenario (428 million m\({}^{3}\)). Thus, under dynamic vegetation conditions, more water is required due to the growth-development-mortality cycle of vegetation, compared to when vegetation maintains growth without mortality. Additionally, increased interception evaporation compensates for the reduction in vegetation transpiration, resulting in a stable total evapotranspiration under the no-vegetation-dynamics scenario. In the no-lateral-flow scenario, water is stored within the soil layers of the upstream forested areas without redistribution to downstream grassland areas; however, transpiration and total evapotranspiration are not significantly affected, indicating that vegetation dynamics in grassland areas are mainly influenced by vertical water recharge. Although the forested areas retain more water, stomatal conductance remains limited by energy, thereby preventing an increase in transpiration. for instream EWRs, increases in runoff with 30% precipitation adjustments are asymmetric, with precipitation increases leading to greater runoff generation. This asymmetry is likely due to the sufficient antecedent soil moisture under relatively humid conditions, where increased precipitation bypasses the need to replenish soil moisture deficits, directly generating runoff, an effect most pronounced at +30% precipitation. Enhanced precipitation intensity leads to water redistribution between green (soil moisture) and blue (surface and groundwater) water resources.