Sensitivity analysis of hydraulic conductivity and Manning's n parameters lead to new method to scale effective hydraulic conductivity across model resolutions

Hydrological modelling is an important tool for research, policy, and management, but uncertainty remains about parameters transferability from field observations made at small scale to models at the catchment scale and larger. This uncertainty compels the need to develop parameter relationships that are translatable across scale. In this study, we compare the changes to modelled processes as resolution is coarsened from 100‐m to 1‐km in a topographically complex, 255‐km² Colorado River headwater catchment. We conducted a sensitivity analysis for hydraulic conductivity (K) and Manning's n parameters across four orders of magnitude. Results showed that K acts as a moderator between surface and subsurface contributions to streamflow, whereas n moderates the duration of high intensity, infiltration‐excess flow. The parametric sensitivity analysis informed development of a new method to scale effective hydraulic conductivity across modelling resolutions in order to compensate for the loss of topographic gradients as resolution is coarsened. A similar mathematical relationship between n and lateral resolution changes was not found, possibly because n is also sensitive to time discretization. This research provides an approach to translate hydraulic conductivity parameters from a calibrated coarse model to higher resolutions where the number of simulations are limited by computational demand.     

基于过程模型的河北平原冬小麦产量和蒸散量模拟

本文结合作物参数的遥感信息反演和气象要素的空间尺度扩展方法 ,建立以GIS背景数据库为支撑的冬小麦生长模型 ,研究河北平原农田生态系统生物量和蒸散量的区域分布特征。结果显示 ,河北平原 1990年高产区主要集中在保定中南部、石家庄中部、邢台中部和邯郸东部的南北条带上 ,单产在 6 0 0 0～ 84 0 0kghm- 2 之间 ,廊坊东部、沧州大部分、衡水中部、邢台东部和西部太行山区等是低产区 ,单产低于 30 0 0kghm- 2 。总体而言 ,该地区实际产量与光温生产潜力对比仍有较大差距。在冬小麦生长期 ,蒸散量主要在 30 0～ 5 0 0mm之间 ,水分利用效率低于2 0kghm- 2 mm- 1,其中小于 8kghm- 2 mm- 1的概率分布占 4 2 %左右。农业水资源不足 ,水分利用效率低 ,是该地区冬小麦生产面临的严重问题。     

四川地区断层空间分布的多重分形特征

断层系统多重分形避免了容量维Ｄ０的不足，考虑了每一条断层对整体分维的贡献，反映了断层的空间分布特征。根据四川地区断层分布图，运用多重分形理论检验了断层空间分布的自相似性，分区计算了四川地区各带的多重分维值。结果表明，断层破裂系统为分形结构，具有很好的自相似性，相关系数均达０．９９。不同带分维值的较大差异，反映不同构造区域的断层分布特点。最后，对分维的含义进行了深入探讨，对油气勘探的有利区域进行了分析。     

应用多重分形法确定老挝窑房地区水系沉积物异常下限

文章阐述了传统的统计学方法与分形含量-求和法求取异常下限的理论模型及步骤,并利用Q-Q图直观地判定了老挝丰沙里省窑房地区水系沉积物中Au,Cu,Pb,Zn元素在地球化学场中不满足正态分布或对数正态分布,而是满足两个层次的分形分布,从而利用最小二乘法拟合各个层次的直线方程求出分维数D,直线相交处对应的ri为各元素的异常下限。地球化学异常场分维数的大小可代表地球化学过程的强烈程度;分形方法圈定的异常范围较大、较连续,利于圈定隐伏、半隐伏矿体形成的弱异常,在红层建造的地层中效果更为显著。     

Contributions of bedrock groundwater to the upscaling of storm‐runoff generation processes in weathered granitic headwater catchments

We examined the contributions of bedrock groundwater to the upscaling of storm‐runoff generation processes in weathered granitic headwater catchments by conducting detailed hydrochemical observations in five catchments that ranged from zero to second order. End‐member mixing analysis (EMMA) was performed to identify the geographical sources of stream water. Throughfall, hillslope groundwater, shallow bedrock groundwater, and deep bedrock groundwater were identified as end members. The contribution of each end member to storm runoff differed among the catchments because of the differing quantities of riparian groundwater, which was recharged by the bedrock groundwater prior to rainfall events. Among the five catchments, the contribution of throughfall was highest during both baseflow and storm flow in a zero‐order catchment with little contribution from the bedrock groundwater to the riparian reservoir. In zero‐order catchments with some contribution from bedrock groundwater, stream water was dominated by shallow bedrock groundwater during baseflow, but it was significantly influenced by hillslope groundwater during storms. In the first‐order catchment, stream water was dominated by shallow bedrock groundwater during storms as well as baseflow periods. In the second‐order catchment, deeper bedrock groundwater than that found in the zero‐order and first‐order catchments contributed to stream water in all periods, except during large storm events. These results suggest that bedrock groundwater influences the upscaling of storm‐runoff generation processes by affecting the linkages of geomorphic units such as hillslopes, riparian zones, and stream channels. Our results highlight the need for a three‐dimensional approach that considers bedrock groundwater flow when studying the upscaling of storm‐runoff generation processes. Copyright © 2014 John Wiley & Sons, Ltd.     

河南省城镇体系空间结构的多分形特征及其与水系分布的关系探讨

基于河南省城镇体系空间结构的多分形性质及其与水系的分维关系的实证探讨发现如下地理规律:①在较大标度范围内,河南省城市体系的空间结构为简单分形,但在较小标度范围内,系统已经具有明确的多重分形特征;②多分维谱在参数q≈-4处出现标度间断,从而城市体系的空间结构发生对称破缺。③城市体系空间结构的分维小于水系空间结构的分维。由此证明:第一,多分形是由单分形演化而来,城镇体系的多分形结构是基于地球表面的分形支体由测度集中区向测度疏散区渐近发育的。第二,城市体系的分形发育与水系的分维结构具有一定的数理关系,城市体系的分维理当小于水系维数。     

紫坪铺水库地区蓄水前后视应力标度率变化研究

本文利用紫坪铺水库台网记录到的波形资料,计算了2004～2008年170个ML≥1.0级地震的震源参数.紫坪铺水库震源参数计算结果与其他大陆地区有明显不同:(1)拐角频率远低于其他大陆地区结果,表明库区地震波传播经过了较强的衰减过程;(2)视应力计算结果比其他地区小3个数量级,可能是由于库区地震波的高频成分衰减强烈,低估了能量集中在高频的小地震的地震辐射能量.分析了蓄水前后拐角频率和地震矩以及视应力和地震矩关系(视应力标度率)变化,结果表明:相同地震矩的地震蓄水后拐角频率增加,地震高频成分相对丰富;蓄水前视应力与地震矩的关系不明显,蓄水后视应力随地震矩的增加而增加.视应力标度率的改变可能是蓄水后地震震源物理过程逐渐改变的直接反映.     

床面粗糙形态的二元分形插值模拟

针对床面粗糙形态具有自相似性的特点,应用二元分形插值迭代函数系统,对床面粗糙形态进行了分形插值模拟,模拟中分形插值邻域Ak根据Kriging空间插值方法的变异函数球状模型确定,垂直比例因子sm,n通过基于插值点数据的多元统计分析确定.结果表明:分形插值重构的床面粗糙形态与原床面形态的相似程度将随着插值点信息量ic的增加...     

基于1km格网的空间数据尺度效应研究

由全国1：10万比例尺资源环境遥感数据库生成的1km格网土 利用／土地覆盖成分数据，分析了依据面积最大原则生成1km单一性值栅格数据与原始成分类型数据之间的误差分布，研究了按照面积最大和中心属性值法从1km栅格数据粗化为4，8和10km栅格数据过程中的误差分布特征，并探讨了地貌特征对这种尺度效应的影响，结果显示，1km单一生栅格数据压缩的城镇及居民点的实际面积（减少多于60％），而增加了林地和旱地的面积，对于单元栅格而言，各类的面积误差（成分面积与尺度转换后保留的单一类型面积之间的差值）与相应尺度栅格范围内的土 地利用复杂程度是对应的，由最大面积法的数据尺度转换引起的误差是随着尺度的增大而增加，而中心属性值法转换过程的误差呈现近似随机分布，应用面积最大法转换空间数据尺度中的误差分布受地貌类型的影响是显著的，水田与旱地面积在数据粗化过程中产生的误差在山地和丘陵区明显高于在其地貌类型上的误差，中心属性值法数据化受地貌类型的影响并不显著。     

连云港海域表层海水温度、盐度变化的多重分形分析

以1996—2008年的连云港海域表层海水温度、盐度的日观测数据为基础,运用多重分形分析方法对该海域温度、盐度的时间演变特征进行了研究。结果表明,在所研究的时间尺度内,温度和盐度均具有统计标度不变性,表现出较弱的多重分形特征;多重分形谱形态参数的计算结果表明,温度和盐度的变化均存在着下降的趋势,并且盐度随时间变化的复杂性、不规则性和不均匀性要较温度显著。研究结果对于连云港海域海洋环境系统动力过程的理解和预报模式的改进具有参考意义。