变化环境下水资源时空格局演变图化方法研究

Mapping large scale regional variations in hydrological behavior has a long tradition in hydrology as well as in other geosciences like meteorology, climatology and geography. The main hydrometerological processes(rainfall, evapotranspiration, temperature etc.) when observed at the land surface develop in a three-dimensional space - the two geographical coordinates (x, y) and time t. The variation of these variables across space is described as contour map sin classical works, i.e. they are space-filling phenomena and allow straight forward interpolation. River discharge (surface runoff), on the other hand, is formed in a two- dimensional space - the distance along a river (related to the point with area A in a basin) and time t . This relationship to the area (and not the (x, y)coordinates) explains why the variation of runoff characteristics across space,determined from discharge measurements, cannot be plotted as simply ashydrometerological variables. Neither is it a space-filling phenomenon. This proposal aims at combining the water balance constraint and stochastic approach for producing choropleth maps of water resourses under changing enviorment. To avoid the uncertainty in hydrological model, this study is just based on data. From singal component (runoff) to multiple components (precipitation, evaporation and runoff), the stochastic approach based on water balance is built. This proved the possibility of combining the geo-statistic and the hydrology. A technique is presented for a joint interpolation of water balance components that considers estimated or observed values with their a-priori uncertainty and yields balanced interpolated values, which respect the water conservation at all levels within the hydrographical network. The approach allows building a consistent water balance pattern, where both the observed values and water balance constraints are given full recognition. The framework presented has strong similarities with assimilation, as it is understood in meteorology (i.e. tuning a model to observed data). It proved to be an excellent diagnostic tool for data in an exploratory phase when investigating patterns of variability. Stochastic interpolation using data from the meteorological and hydrological networks were used to produce a set of prior digital maps of precipitation, actual evapotranspiration and runoff. The new theory is then used to analyze the water resources of Huai River basin in changing environment. It would be of great value for ensuring water supply in this densely populated part of China to get insight in the water cycle in the basin and follow its development in time. The results are meant to be used in a larger project on Water Atlas of China, as a next step of research.

由于气候变化和高强度人类活动的影响导致流域下垫面变化的复杂性，跨时空尺度水文图化（Mapping）的研究已成为当前国际水文科学研究的热点前沿问题，其关键科学问题是构建基于水平衡理论的空间插值方法。本项目将流域水循环及水量平衡物理制约关系与水文要素的空间插值方法相结合，提出流域尺度下径流空间插值算法，建立径流空间插值不确定性评价体系；通过将垂向水量平衡约束条件加入到空间插值方法中，建立降雨、蒸发、径流深三者之间的相关关系，提出一种基于水循环多要素联合空间插值的水文图化方法，并将其应用于我国典型流域，分析变化环境下水文要素的时空分异特征，为揭示变化环境下流域水资源时空格局演变提供新方法。该项研究对推动水文学的发展和流域水资源管理有重要的意义。

本论文的研究特色是将流域水循环及水量平衡物理制约关系与地理分异的空间插值方法相结合，研究变化环境下水资源的时空分异特征，发展针对水文要素的空间插值图化方法，以避免因水文模拟环节增加而带来的不确定性。通过从单要素（径流）到多要素（降雨、蒸发、径流）的空间综合模拟，逐步建立了从水平方向到垂向的水平衡随机模拟方法。提出的研究成果在我国淮河流域得到了初步应用于验证，证明了地理统计原理与水文过程深层次结合的可能性，并提出若干值得在水文研究中广泛推广的理论方法和经验。论文的主要结论如下：.1、建立了径流空间插值方法不确定性评价体系：径流的空间变异具有较强的不确定性，为了得到一种径流插值方法的可信度及对比不同空间插值方法的优劣，文中利用栅格、河道插值估计误差等统计指标，结合交叉检验建立了径流空间插值不确定性评价体系，通过该体系可以确定地给出某种方法的不确定性。利用该评价体系还可以对多种径流空间插值方法进行对比分析，找出适合给定研究区的最优径流空间插值方法，为进一步开展多要素联合插值研究提供基础。.2、提出了基于水平衡关系的多要素联合图化方法：通过在降雨、蒸发、径流三者空间插值结果之间建立相关关系，解决了以往水文三要素模拟过程中各自独立的问题，成功的将垂向水量平衡约束条件加入空间插值方法，实现了水文过程三要素的联合图化。联合插值方法考虑到了插值误差和数据误差，并产生新的纠正后插值结果，该结果可以保证在所有水文地理层次上的水量守恒。.3、提出基于信噪比的多尺度水文要素图化可信度规律分析方法：为了识别水文空间跨尺度融合过程中的分辨率阈值，对插值结果的精度有量化把握，本文提出了利用空间插值信噪比的概念来计算最优精度的方法，通过大量实验证明了给定数据条件下空间分辨率阈值的存在。该分辨率也可以理解为针对给定数据资料的最优输出分辨率。在该最优分辨率下，图化结果的信息量与噪声量的比值达到最大，能够为人们提供最多的有效信息。