Collaborative Research: Scaling and Allometry in River Networks: Coupling Rainfall, Topography, and Vegetation with Hydrological Extremes

合作研究：河流网络的尺度和异速生长：降雨、地形和植被与水文极端情况的耦合

• 批准号: 0001249
• 负责人: Witold Krajewski
• 金额: $ 10.02万
• 依托单位: University of Iowa
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0001249&HistoricalAwards=false
• 关键词: Collaborative; Research; Scaling; Allometry; River

0001249KrajewskiThe long-term goal of this research is to develop an allometric-hydrologic scaling theory for drainage basins, which can be applied to global drainage networks. We define hydrologic-allometry scaling to mean the existence of empirical power-law relationships among hydrological, ecological, topographical and atmospheric variables and mass of water being transported in drainage networks or physically relevant space-time scales. This research aims to synthesize a wide variety of disparate empirical observations within a broad theoretical framework.The first major objective of this proposal is to develop a theory for extrapolating observed streamflow time series from a few sparsely located stream gauging stations to ungauged locations defined by complete Strahler streams. Spatial extrapolation requires that streamflows be separated into peakflow and lowflow time series because different time scales are inolved in runoff generation and transport in physically based filter to separate lowflows from peakflows of gauged locations. Diagnostic tests of this filter will be carried out using available in-situ measurements of rainfall, evaporation and gauged streamflows. An integrated numerical model of runoff generation processes from a hillslope will be used to test the filter as part of these diagnostic studies. Another key step is to develop a testable space-time theory to route water in channel networks. Our approach will attempt to combine observations of hydraulic geometry, principles of fluid mechanics such as conservation of mass, and property of random self-similarity recently reported in the topology of channel networks. The second objective is to extend the results in objective 1 to incorporate the effect of spatial variability in rainfall, evapotranspiration and runoff generation processes. This objective will be investigated in two steps. First will be to estimate space-time rainfall at one sq. km. Pixels every 6 minutes using WSR-88D radar estimates. Evapotranspiration (ET) and soft moisture in the rooting zone will be estimated from remotely sensed products, e.g., moderation resolution imaging spectrometer (MODIS). Second step will be to test the sensitivity of the filter and the routing developed in Objective 1 to spatial variability in rainfall, evapotranspiration, and runoff generation, using these remotely sensed products. Effect of error structure in remotely sensed products on the filter and the routing will be investigated. Comparisons of these results with those obtained under Objective 1 will be carried out to understand the robustness of the filter and routing to errors in remotely sensed products. We will test Objectives 1 and 2 on a few selected basins, e.g., Flint in Georgia, which is about 7,000 sq. km. The existing digital elevation models (DEM) will be used to extract network structure for geomorphologic analysis. In the long run, a 'test of the concept' involving new measurements is needed for a few basins serving as 'natural laboratories,' but field tests are outside the scope of this proposal. Progress on these two objectives will make contributions toward the classic, long-standing, unsolved hydrology problem of Prediction from Ungauged Basins (PUB).Our third objective is to investigate empirical allometric-scaling relationships, and assess space-time scales over which scaling holds. Suitable biophysical constraints involving the coupling of atmosphere, terrain, water, and vegetation will be identified for river networks. We will carry out some exploratory studies on this objective. The new Shuttle Radar Topographic Mission (SRTM) and MODES products provide global topographic and vegetation data sets respectively. Satellite-based estimates of space-time rainfall seems less attractive at this point mainly due to their poorer spatial and temporal resolution but this situation would change in the future. Use of these remotely sensed products in developing and testing this theory would make it feasible to explore applications to global networks in the future.

这项研究的长期目标是发展一种适用于全球排水网络的流域异速生长-水文标度理论。我们定义水文异速生长尺度是指水文、生态、地形和大气变量与在排水网络或物理上相关的时空尺度中输送的水量之间存在经验的幂定律关系。这项研究的目的是在一个广泛的理论框架内综合各种不同的经验观测。这项建议的第一个主要目标是开发一个理论来外推从几个稀疏的流量测量站到由完整的Strahler流定义的未测量位置的观测流量时间序列。空间外推要求将径流分为洪峰流量和枯水流量时间序列，因为物理滤池在径流产生和输运过程中涉及不同的时间尺度，以区分实测位置的枯水和洪峰流量。该过滤器的诊断测试将使用现有的降雨量、蒸发量和测量径流流量的现场测量进行。作为这些诊断性研究的一部分，将使用从山坡产生径流过程的综合数值模型来测试过滤器。另一个关键步骤是开发一种可测试的时空理论，以在渠道网络中引导水。我们的方法将尝试结合水力几何的观测，流体力学的原理，如质量守恒，以及最近在河网拓扑中报道的随机自相似性质。第二个目标是扩大目标1中的结果，以纳入降雨、蒸散和径流产生过程中的空间变异性的影响。这一目标将分两步进行调查。首先是估计1平方英尺的时空降雨量。公里。每6分钟像素使用WSR-88D雷达估计。蒸散量(ET)和根区的软水分将由遥感产品估算，例如适中分辨率成像光谱仪(MODIS)。第二步是使用这些遥感产品测试目标1中开发的过滤器和路线对降雨量、蒸散量和径流产生的空间变异性的敏感性。将研究遥感产品中的误差结构对滤波和布线的影响。这些结果将与目标1下获得的结果进行比较，以了解过滤器的稳健性和对遥感产品中的错误的选择。我们将在几个选定的盆地测试目标1和目标2，例如佐治亚州的弗林特，面积约为7,000平方英尺。公里。将现有的数字高程模型(DEM)用于提取地貌分析的网络结构。从长远来看，需要对几个作为“天然实验室”的盆地进行涉及新测量的“概念测试”，但现场测试不在这项提议的范围之内。这两个目标的进展将有助于从未测量的盆地预测(PUB)的经典的、长期存在的、未解决的水文学问题。我们的第三个目标是研究经验的异速生长-尺度关系，并评估尺度适用的时空尺度。将为河网确定适当的生物物理约束，包括大气、地形、水和植被的耦合。我们将对这一目标进行一些探索性研究。新的航天飞机雷达地形任务(SRTM)和MODS产品分别提供全球地形和植被数据集。在这一点上，基于卫星的时空降雨量估计似乎不那么有吸引力，主要是因为它们的空间和时间分辨率较差，但这种情况在未来将会改变。使用这些遥感产品来开发和测试这一理论，将使其在未来探索全球网络的应用成为可能。