Tsugihiro Watanabe

Soil salinization in the Nile Delta and related policy issues in Egypt

Abstract The soil salinization problem in Egypts Nile Delta and related policy issues are addressed in regards to the need to create water supplies for new irrigation projects by, for instance, re-use of irrigation drainage waters and limits on rice plantings, and at the same time improving the agricultural productivity of the Nile Delta through, for instance, subsurface drainage in water-logged lands, land leveling and use of gypsum amendments. A brief background on the climate, agriculture and crop rotation patterns, and water and land resources and their salinities is provided. The paper describes countermeasures taken by the government on a national and regional scale and farmers on a local or field scale. The farmers participatory role in adapting to changes in cropping, water and soil salinity, and national needs are crucial. Emphasis is laid on the advantages and benefits of rice cultivation in drainage- and salt-impacted lands of the northern Delta. But use of rice paddies to control salinity is faced with a number of constraints such as periodic shortfalls in supply of irrigation water, salinity of supply waters consisting of a blend of fresh and drainage waters and diversified cropping, including rice, in a given subsurface drainage system. We strongly support the recommendations for rice cultivation only in saline soils of the Delta but perceive that enforcement of such a policy may be difficult to achieve and long-term changes in salinity of delta waters are not clearly known with increased drainwater re-use.

A general adaptation strategy for climate change impacts on paddy cultivation: special reference to the Japanese context

Climate changes due to global warming may affect paddy cultivation considerably. Climate changes directly affect rice plant growth, and within paddy cultivation catchments, alter the hydrological regime including flood patterns and water availability for irrigation, and drainage. Although increased atmospheric CO2 concentrations in the future may enhance plant growth through the CO2 fertilization effect, impacts of climate change on agriculture are complicated and difficult to predict precisely. This is especially the case for assessing impacts on paddy cultivation, where basin hydrological behavior needs to be understood in detail. Possible adaptations to reduce negative impacts should be tailored to local conditions, which modify climate change impacts on paddy cultivation. In this article, climate change impacts on paddy cultivation are reviewed and a general adaptation strategy is discussed with special reference to the Japanese context.

Modeling interaction of fluid and salt in an aquifer/lagoon system.

To simulate the dynamic interaction between a saline lagoon and a ground water system, a numerical model for two-dimensional, variable-density, saturated-unsaturated, and coupled flow and solute transport (saltwater intrusion by finite elements and characteristics [SIFEC]) was modified to allow the volume of water and mass of salt in the lagoon to vary with each time step. The modified SIFEC allows the stage of a lagoon to vary in accordance with a functional relation between the stage and water volume of the lagoon, and also allows the salt concentration of the lagoon to vary in accordance with the salt budget of the lagoon including chemical precipitation and dissolution of salt. The updated stage and salt concentration of the lagoon are in turn used as transient boundary conditions for the coupled flow and solute transport model. The utility of the modified model was demonstrated by applying it to the eastern Mediterranean coastal region of Turkey for assessing impacts of climate change on the subsurface environment under scenarios of sea level rise, increased evaporation, and decreased precipitation.

Seasonal changes of fertilizer impacts on agricultural drainage in a salinized area in Adana, Turkey

Seasonal changes in the impacts of fertilizer on the composition of agricultural drainage water were examined by analyzing the (87)Sr/(86)Sr isotope ratio and chemical composition of drainage water samples. Samples of drainage water were taken from the main drainage canals of the Lower Seyhan Irrigation Project, at sites designated as D10, D11, and D12. Plots of (87)Sr/(86)Sr vs. 1/Sr indicated that the (87)Sr/(86)Sr ratio of drainage water was positively related to those of fertilizer and irrigation water. The origins of Sr in two of the end-components were fertilizer and irrigation water. The data from the end-drain in winter suggested that the origin of Sr in the third end-component was fossil seawater. Analysis of a mixing model incorporating these three end-components showed that the origins of Sr in drainage differed markedly between summer and winter. Fertilizer made the greatest contribution to Sr in drainage water both in summer and winter, contributing 38-72% of total Sr in summer and 64-87% of total Sr in winter. In summer, fertilizer contributed 72% of total Sr in drainage water in D12, 44% in D10, and 38% in D11. This result implies that fertilizer was applied excessively at the D12 site. In winter, seawater accounted for 10% of Sr in drainage water in D12, whereas it accounted for 19-27% of Sr in drainage water in D10 and D11. Therefore, at least 70% of the salt in drainage water originates from fertilizer and irrigation water. At this study site, the salt originating from seawater is replaced by that from fertilizer and irrigation water, due to intensive agricultural management. The study site is a delta that lay on the ocean subsurface at least 3000years ago, and therefore, was originally a primary salinization area. This result suggests that anthropogenic secondary salinization progressed over time via fertilizer and irrigation applications.

The Anthroscape Approach in Sustainable Land Use

The final outcomes of the approach of the anthroscape, seeking to develop a powerful tool for use by the local communities/administrations and relevant bodies for a bottom to top approach, as a quantified entity, means to direct the future land and water use decisions to be taken at lower levels – as farm domains etc. – leading to the development of an “Anthroscape Land Quality Class” map and the relevant “Ideal Land Use Patterns” of the Seyhan Anthroscape. These two final products of quantification are sought to be capable in revealing the magnitude and the distribution of the degradation of the selected area, as well as allocating the ideal land use types given for the percentages of the distributions of land except their specific location. In this context, the downstream part of the map will show the abundant degradation arising via the intensive cultivation practices where the class stated in the map reveals the urgent need of an integrated SLWM Programme to revert the lower class C and D ALQCs to higher ALQCs to meet the requirements of the sustainable use of the land. Whereas, the higher ALQC land in the transition or upstream zone stands for higher resilience and lower input requirements to meet the ideal use of the land. The Net Primary Production (NPP) – The remainder of photosynthesis and respiration – which has significance in the global and regional carbon budgets and is a function of the standing biomass (an important component of the carbon cycle and a key indicator of ecosystem performance) was utilized via land cover and management to serve as a supplementary indicator of the Anthroscape and the Anthroscape Land Quality.

Local Wisdom of Land and Water Management: The Fundamental Anthroscape of Japan

With the combination of the advanced prediction and the traditional knowledge like Mitameshi, we can foster local wisdom for wise land and water management and improvement of the regional environment. Such an approach may be effective in solving the problems caused by global climate changes resulting in living of humans in harmony with nature, which means living in a better anthroscape. Ultimately, the wisdom of Suido is to be sublimed to the context of “ecosophy”.