Integrate water constraints in optimized land spatial allocation: Part One: the strategy

Alex Li
4 min readJul 11, 2020

What’s happening in the world?

The global water scarcity (Sources: https://advances.sciencemag.org/content/advances/6/18/eaaz6031/F2.large.jpg?width=800&height=600&carousel=1)

For the past decades, we have been facing global climate change, and poverty and starvation have raised major concerns for people. According to Lorenzo Rosa and others’ paper published on Science Advances in April of 2020, we have known more precise condition about water and agriculture: 23% of global cropland areas are irrigated, and up to 25% of the global croplands are affected by agricultural economic water scarcity. To fight starvation and meet high demands from food, water and lifestyle, one of the key measurement is how to use natural resources more wisely, especially land and water which are closely and complexly interrelated, from macro-scaling water circulation, precipitation and farmland location for nations, to micro-scaling soil content and cropping pattern on plots. In many countries, issues concerning land and/or water such as shortage of farmland and its productivity per capita, unbalanced water resources for land, expanding build-up areas and human activities neglecting environmental impacts, are rising siren for communities, scientists, planners and officials globally.

The whole world has progressed much more on land and water management. Smart agriculture, water-saving irrigation supported by technical updates such as 3S, and institutional reform are boosting better utilization of natural resources. For countries like USA and Australia which have more arable land per capita and flat farms, have progressed into environment protection and institutional reform such as TVA and MDBA. But in countries like China and India which have much more population and traditional farming skills with fragmented peasant organizations, the key point is how to use land and water much more wisely other than systematic reforms.

The global arable land and farm size (Source: https://www.fastcompany.com/3042106/the-most-detailed-map-ever-of-the-worlds-cropland-so-we-can-decide-where-to-grow-more-food)

As a former land use planner and senior water policy consultant for ministries, my team and I have done some projects concerning water and land resource management in North China. The aim was to highlight the methodology of agricultural land-water balance, optimization and its spatial allocation in water deficient regions, in order to arise attention of smart agriculture and water-saving strategy in broader areas.

The strategy of spatial allocation of optimized land and water

China’s land and water resources are mis-matched for seasons. South China holds 45000 cubic meters per hactre for farmland, nearly 10 times higher than that in North China, but only 56% in area compared to North China. The mis-matching condition in Yellow-Huai-Hai(HHH) Plain in North China is more serious: 38.5% area of whole country’s farmland holds only 7.6% national available water resources!

Mechenized operation on HHH Plain (Source: http://www.xingtang.gov.cn/zxdt/shxw/4572.html)

How to produce food with less water and environmental impacts is key point for local government. And we helped one city government with scientific supports and strategies with geospatial skills.

Step one: we made the system of agricultural land-water resources whose essence was the efficiency and benefits of land-water coupling.

Step two: we scrutinized the status quo of farmland with GIS and agricultural water, which was integrated by the regularity, pattern, driving forces and carrying capacity of land intensive utilization, and the features of crop water requirements, ecological water requirements, and agricultural available water resources.

Step three: we modified the BUDGET model which was firstly constructed for plot scale researches, and then demonstrated the spatial-temporal features of field water balance with this modified model in order to show the pressures indices on farmland and agricultural water of 16 counties for different years.

Step four: we optimized agricultural land and water by scenarios analysis approach with assistance of Matlab Optimization Toolbox. The scenarios were based on the multiple-goal, including maximizing the profits from crops and the outputs of grains, and minimizing the water requirements of crops which was also called “water restraints” as the results of agricultural available water in status quo research.

Step five: we allocated the optimized land resources according to scenarios. Based on the suitability evaluation model integrated with natural conditions, socioeconomic factors, the utilization of resources and the pressures of resources, we set up a routine to allocate 6 major types of crops once each to show where the specific crop would be planted and to which extent the current planting areas needed to be revised using ArcGIS.

Step six: we concluded with some suggestions and strategies for local government.

Analysis strategy

There will be detailed posts about key findings using modern GIS and econometric analyzing skills.

Thanks for reading, and welcome replies:) That will be a great opportunity for sharing views.

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Alex Li

A senior policy consultant, GIS user, and land-water industry adviser. Love to investigate current policies and show better managing skills.