Stream network extension and contraction depend on landscape features and the characteristics of precipitation events. Although this dependency is widely recognized, the interaction among overland-flow generation processes, drainage active length, and frequency in temporary streams remains less understood. We studied a forest headwater catchment with wide variation in soil depth to investigate the runoff generation processes that lead to the occurrence of ephemeral and intermittent flow and connectivity between hillslope and outlet. We used low-cost equipment to monitor the variation in the length of the active drainage network and to measure the water table development. The flow in the channels can develop even under light rainfall conditions, while the connectivity is controlled by antecedent wetness, total precipitation, and active contribution area thresholds. Runoff permanence and fragmentation were related to soil depth variation; flow being usually more disconnected due to deeper water tables in deeper soil locations. Our findings emphasized the impact of soil structure on runoff generation in hillslopes and can be useful in the management of the most active areas and their impact on the quality of available water.
The quantification of baseflow is key for water resources management. However, there are few reports on the precision and accuracy in low streamflow measurements. In this paper, we systematically analyze the precision and accuracy of dilution streamflow measurements in headwater channels during baseflow. Precision refers to the variability of the values for repeated measurements and accuracy is how much the measured value approximates the reference one. We measured streamflow in 31 different cross-sections with contributing areas ranging from 0.02 to 5.33 km2. Streamflow measurements with the current meter were adopted as reference for accuracy estimation. A precision error of ±5.0% was found for the measurements. The percent errors compared to reference streamflow ranged from 0.7 to 45.6%, with a median of 6.1%. Precision and accuracy are in the same order of magnitude found in the literature for larger streams. These results can be used for constraining the uncertainty of streamflow measurements and rainfall-runoff modeling of headwater streams.
The Peri Lake Experimental Catchment, in Southern Brazil, is a small coastal lake (5 km 2 , 7 m depth) with a total catchment area of 20 km 2. The catchment is mainly covered by subtropical Atlantic Forest. Peri Lake is a recreational destination, an important ecosystem for biodiversity preservation, and a major water supply source. Even though there is a clear social and economic relevance, the information on this ecosystem is scarce, especially regarding the dynamics of water balance and water quality. We built this observatory using a low-cost, low-technology monitoring system to estimate the major components of the water budget on what we called a critical budget. We monitor meteorology, rainfall interception in two plots, overland flow and groundwater connectivity in a representative hillslope; and streamflow and velocity are measured in several small headwater rivers mostly starting during 2015. Geographic information on topography, land cover, geology, soil characteristics and
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