Furrow irrigation when combined with plastic mulch on ridge is one of the current uppermost water-saving irrigation technologies for arid regions.The present paper studies the dynamics of soil water-salt transportation and its spatial distribution characteristics under irrigation with saline water in a maize field experiment.The mathematical relationships for soil salinity,irrigation amount and water salinity are also established to evaluate the contribution of the irrigation amount and the salinity of saline water to soil salt accumulation.The result showed that irrigation with water of high salinity could effectively increase soil water content,but the increment is limited comparing with the influence from irrigation amount.The soil water content in furrows was higher than that in ridges at the same soil layers,with increments of 12.87% and 13.70% for MMF9(the treatment with the highest water salinity and the largest amount of irrigation water) and MMF1(the treatment with the lowest water salinity and the least amount of irrigation water) on 27 June,respectively.The increment for MMF9 was gradually reduced while that for MMF1 increased along with growth stages,the values for 17 August being 2.40% and 19.92%,respectively.Soil water content in the ridge for MMF9 reduced gradually from the surface layer to deeper layers while the surface soil water content for MMF1 was smaller than the contents below 20 cm at the early growing stage.Soil salinities for the treatments with the same amount of irrigation water but different water salinity increased with the water salinity.When water salinity was 6.04 dS/m,the less water resulted in more salt accumulation in topsoil and less in deep layers.When water salinity was 2.89 dS/m,however,the less water resulted in less salt accumulation in topsoil and salinity remained basically stable in deep layers.The salt accumulation in the ridge surface was much smaller than that in the furrow bottom under this technology,which was quite different from traditional furrow irrigation.The
In the Shulehe River Basin, policy of resettlement was very effective in handling agricultural development and livelihood problems in regions of poverty limited by topography, climate, or infrastructure. Thus, since 1996–1997, the Shulehe River Basin resettlement project transferred roughly 7.5×104 people from areas of Dingxi, Longxi or Minxian which could not offer sufficient resources for the residents. Meanwhile, construction facilities such as the reservoir, which underpins the resettlement project, also triggered an internal migration of people away from the reservoir to other parts of the Shulehe River Basin. This large scale migration derived apparent effects in water resources, land use and cover change, agricultural structure as well as landscapes. Results show that total arable land expanded by 3.1×108 m2, cattle numbers maintained a stable level of 1×104, pigs declined to a low level due to market trends, and sheep numbers soared from 17.44×104 to 73.57×104. However, greening and afforestation increased while croplands maintained a rational tendency accompanying with greening area expansion. From the standpoint of integration, the Shulehe River Basin resettlement policy fulfilled its previous goals of improving the inhabitants' livelihood and the capacity of environment when spatial residues including environmental capacity and resources consumption for sustainable development are still positive conditions.
