| Water is a very important ecological constraint for vegetative constrution in the desert region, it mainly exists in the form of soil water, and soil water is a key interconversion link between surface water, groundwater and atmospheric water, it plays an important role in the formation, transformation and consumption of water resource. Rainfall infiltration recharge is soil water’s main supply source in the desert region, and at the same time, the deep soil moisture infiltration is a key link for to transform atmospheric water into groundwater, and it is vital in the formation of underground water resources. Therefore, system analysis of different type dunes soil moisture dynamics and water deep infiltration characteristics is important for the study of Eco-hydrological processes, and it could guide the construction of vagetative cover, the evaluation on revegetated stability, and the assessment of water resources in the desert region. The AV-3665R-type rain sensor, ECH2O-5 soil moisture sensor and Deep Soil Infiltration Water Recorder were used to monitor precipitation quantitatively, soil water for 0~200cm deep and soil water leakage below 200 cm in the mobile dune, A. ordosica semi-fixed dune, A. ordosica fixed dune, S. psammophila fixed dune and P. sylvestris fixed dune of the Mu Us Sandland in 2013~2014. Combined with the weather, rainfall interception, surface soil moisture measurement system, analysis of the different type dunes of soil moisture dynamics, deep infiltration characteristics and differences for soil water recharge, estimated water balance of different dunes. The results were shown as follows:(1) Rainfall interception in descending order of P. sylvestris fixed dune, S. psammophila fixed dune, A. ordosica fixed dune, A. ordosica semi-fixed. Estimates result for A. ordosica semi-fixed, A. ordosica fixed dune, S. psammophila fixed dune, P. sylvestris fixed dune rainfall interception were 13.3mm, 23.4mm, 26.7mm, 34.0mm in 2013(Rainfall 405.6mm) and 16.9mm, 29.2mm, 33.9mm, 42.6mm in 2014(Rainfall 322.2mm), respectively.(2) Different type dunes of surface 0~10cm soil moisture content decreased rapidly after the first day of rain, and the rate of decrease declined slowly afeterwards; where A. ordosica fixed dune and P. sylvestris fixed dune after rain water fall trend slow than mobile dune, A. ordosica semi-fixed, S. psammophila fixed dune, and high moisture content. Surface soil water volume content and rainfall, relative humidity were significant positive correlation(P<0.01), but fitting equation predicts the effect of surface soil moisture poorly. Consistent with the different type dunes of surface soil moisture evaporation process, the strongest evaporation is in July, the maximum amount of evaporation is also for the first day after rainfall, and 0~5cm layer of evaporation is higher than 5~10cm layer; where of the soil’s daily maximum amount of evaporation was mobile dune(2.95mm) in 0~5cm layer; daily maximum evaporation was A. ordosica semi-fixed dunes in the 5~10cm soil layer(1.45mm).(3) Rainfall significantly(P<0.01) affects 0~200cm soil moisture in different type dunes, in which 10 cm, 30 cm and 60 cm of soil moisture were affected largely by rainfall, 90 cm below the soil only by larger rainfall or more concentrated small rainfall events, the frequency fluctuations after rainfall is in the order of mobile dune > A. ordosica semi-fixed > A. ordosica fixed dune, S. psammophila fixed dune and P. sylvestris fixed dune, and the stronger affected by rainfall for soil layer were 0~60cm of mobile dune, 0~90cm of A. ordosica semi-fixed dune, 0~60cm of fixed dune(A. ordosica, S. psammophila and P. sylvestris). At the same time, the maximum of monthly average soil volume moisture was P. sylvestris fixed dune in the soil at 10 cm and 30 cm, the largest was mobile dune at 60~200cm layer, indicating the soil moisture was consumed after the establishment of vegetation, and changing the soil moisture redistribution process after rainfall, moreover, rainfall intensity, rainfall amount, and rainfall frequency were all affecting soil moisture response after rainfall.(4) Under the same rainfall condition, mobile dune showed the characterstic that a shorter infiltration time would need a smaller rainfall amount, when lower average moisture of 0~30cm, 53.8mm(Rainfall time 71h) rainfall was able to infiltration into the 200 cm soil after rainfall 15 days in the mobile dune, S. psammophila fixed dune and P. sylvestris fixed dune, infiltration time was 306 h, 310 h and 335 h, respectively. However, this rainfall was not able to infiltration into the 150 cm soil after rainfall 15 days in the A. ordosica fixed dune. When higher average moisture of 0~30cm, 88.6mm(Rainfall time 63h) rainfall was able to infiltration into the 200 cm soil after rainfall 15 days in the mobile dune, A. ordosica semi-fixed, A. ordosica fixed dune, S. psammophila fixed dune and P. sylvestris fixed dune, infiltration time was 57 h, 69 h, 133 h, 70 h and 86 h, respectively.(5) Under the same conditions of rainfall, The maximum of below 200 cm deep leakage was mobile dune, which in 2013 leakage 144.2mm, 2014 leakage 40.3mm, account for 35.5% and 11.0% of the rainfall, respectively, followed by A. ordosica semi-fixed, fixed dune few. The maximum leakage supply days was mobile dune, followed by A. ordosica semi-fixed, the least were fixed dune, daily maximum leakage and daily leakage, too. Rainfall patterns were the main factors that affect deep leakage of mobile dune, semi-fixed dunes was affected by the double impact of rainfall pattern and vegetation cover, however, fixed dune was mainly affected by vegetation cover.(6) Mobile dune, A. ordosica semi-fixed, A. ordosica, S. psammophila and P. sylvestris fixed dune can maintain water balance in 2013(Rainfall 405.6mm), and the amount of recharge were 181.6mm, 69.3mm, 34.5mm, 24.8mm, 13.9mm, respectively. Mobile dune, A. ordosica semi-fixed, S. psammophila fixed dune and P. sylvestris fixed dune can maintain water balance in 2014(Rainfall 322.2mm), however, A. ordosica fixed dune(Coverage > 70%) cannot maintain water balance and water deficit was 22.4mm. |
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