Determining the influence of irrigation efficiency improvement on water use and consumption by conceptually considering hydrological pathways

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Published in Agricultural Water Management

Ling Zhang, Qimin Ma, Yanbo Zhao et al.

ABSTRACT: Improving irrigation efficiency is widely believed to be a promising opportunity for large water savings. However, more and more voices have been raised against this idea in recent years. This study investigated the impacts of irrigation efficiency improvement on water use and consumption by combining an agro-economic model with the conceptualization of hydrological pathways. The investigation was conducted under two different conditions, i.e., Case 1: unlimited water supply and restricted irrigatable land, and Case 2: limited water supply and unrestricted irrigatable land. At the scale of the WUU, we found that the water uses could be reduced significantly after improving irrigation efficiency, while the water consumptions would be of similar magnitudes for different irrigation techniques under the condition of Case 1. However, in the condition of Case 2, the water uses would be inelasti[……]

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Separating climate change and human contributions to variations in streamflow and its components using eight time‐trend methods

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Published in Hydrological Processes

https://onlinelibrary.wiley.com/doi/abs/10.1002/hyp.13331

Separating climate change and human contributions to variations in streamflow and its components using eight time‐trend methods

Ling Zhang,  Zhuotong Nan, Weizhen Wang, et al.

Abstract

Separating impacts of human activities and climate change on hydrology is essential for watershed and ecosystem management. Many previous studies have focused on the impacts on total streamflow, however, with little attentions paid to its components (i.e., baseflow and surface runoff). This study distinguished the contributions of climate change and human activities to the variations in streamflow, baseflow and surface runoff in the upstream area of the Heihe River Basin, a typical inland river basin in northwest China, by using eight different forms of time‐trend methods. The isolated contributions to streamflow variation were also compared with those obtained by two Budyko‐based approaches. Our result[……]

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Matlab codes for two breakpoint checken

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(1)  累计距平均

data=xlsread(‘test.xlsx’);

data(:,1)=[];

mean_data=mean(data);

diff_streamflow=data(:,1)-mean_data(1);

diff_baseflow=data(:,2)-mean_data(2);

diff_surfq=data(:,3)-mean_data(3);

Sum_streamflow_anomaly=zeros(55,1);

Sum_baseflow_anomaly=zeros(55,1);

Sum_surfq_anomaly=zeros(55,1);

for i=1:55;

Sum_streamflow_anomaly(i)=sum(diff_streamflow(1:i));

Sum_baseflow_anomaly(i)=sum(diff_baseflow(1:i));

Sum_surfq_anomaly(i)=sum(diff_surfq(1:i));

end

years=(1960:2014)’;

xlswrite(‘cumulative_anomaly.xlsx’,[years,Sum_streamflow_anomaly,Sum_baseflow_anomaly,Sum_surfq_anomaly])

通过绘图找到分界点即得到break point

(2)   Pettitt检测

% This code is used to find the change point in a univariate continuous time series

% using Pettitt Test.

%

%

% The test here assumed is two-tailed test. The hypothesis are as follow:

%  H (Null Hypothesis): There is no change point in the series

%  H(Alternative Hypothesis): There is a change point in the se[……]

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A paper published in JoH

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Application of the MacCormack scheme to overland flow routing for high-spatial resolution distributed hydrological model

Although process-based distributed hydrological models (PDHMs) are evolving rapidly over the last few decades, their extensive applications are still challenged by the computational expenses. This study attempted, for the first time, to apply the numerically efficient MacCormack algorithm to overland flow routing in a representative high-spatial resolution PDHM, i.e., the distributed hydrology-soil-vegetation model (DHSVM), in order to improve its computational efficiency. The analytical verification indicates that both the semi and full versions of the MacCormack schemes exhibit robust numerical stability and are more computationally efficient than the conventional explicit linear scheme. The full-version outperforms the semi-version in terms of simulation accuracy when a same time s[……]

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