Abstract
We developed an advanced design programmable rainfall simulator (RS) to simulate a moving storm rainfall condition. The RS consists of an automated nozzle control system coupled with a pressure regulator mechanism for an operating range of 50 kPa to 180 kPa at a drop height of 2000 mm above the soil flume surface. Additionally, a programmable mobile application was developed to regulate all RS valves. Near natural rainfall conditions were simulated at varying spatial and temporal resolutions in a controlled environment. A soil flume of 2500 mm × 1400 mm × 500 mm was fabricated to conduct different hydrological experiments. The flume was designed to record overland, subsurface, and base flows simultaneously. This study focused on a detailed analysis of moving storms and their impact on hydrograph characteristics. Experimental results showed a considerable difference in terms of time to peak (tp), peak discharge (Qp), and hydrograph recession for two different storm movement directions (upstream and downstream). Two multiple regression models indicate a statistically significant relationship between the dependent variable (tp or Qp) and the independent variables (i.e. storm movement direction, storm velocity, and bed slope gradient) at a 5 % level of significance. Further, the impact of these moving storm phenomena reduces with the increase in the storm movement velocity.
Highlights
Due to high variability in storm pattern, intensity, storm movement velocity, direction, and rainfall drop sizes, it is often 15 challenging to study rainfall characteristics and impacts on overland flow, subsurface flows, baseflows, and soil erosion at a watershed-scale (Singh, 1998)
3 Results and discussion After completing the design of the moving storm rainfall simulator (RS) (Figure 6), we checked the feasibility of the RS for generating the moving storm events
Upstream Downstream Upstream Downstream Upstream Downstream Upstream Downstream Upstream Downstream Upstream Downstream the plot was analyzed (Figure 7). It can be elucidated from the rainfall distribution graph that 70% of the plot area receives a uniform amount of rainfall, i.e., 30 mm to 36 mm
Summary
Due to high variability in storm pattern, intensity, storm movement velocity, direction, and rainfall drop sizes, it is often 15 challenging to study rainfall characteristics and impacts on overland flow, subsurface flows, baseflows, and soil erosion at a watershed-scale (Singh, 1998). Rainfall simulation is one such method that is cost-effective and is used to study hydrological processes under controlled rainfall conditions (Nanda et al, 2018). Rainfall simulation refers to the process of simulating rain in a confined area for a specific time at a controlled rate. Rainfall simulator (RS) is an efficient instrument that enables quick data collection and analyses of a wide range of processes and treatment measures based on the variants of simulation configuration as per the study’s objectives (Silveira et al, 2017). Rainfall simulation experiments were developed by the United States Soil Conservation Service (SCS) in the 1930s to measure erosion potential and infiltration capacity of the soils.
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