مجله ترویج و توسعه آبخیزداری
پیاپی 4 (بهار 1393)

The aim of this paper is assessment drought indicators in Hormozgan province. we have used the rain and temperature data for Bandar Abbas, Jask, Lengeh, Minab, Kish, Siri and Abomoosa stations for the period of1986-2005. Then, RDI drought indicators then was calculated. We assign frequency of drought and humid years. The research outcomes show drought is weak and severe in several of years in all of the stations and in most of stations drought is normal. Hormozgan province have propitious condition in 1995 and 1997 years because of Kish and Gheshm stations are normal and other stations have very humid and almost humid condition. Most of drought frequency occur in Banda Abbas and Lengeh station with 5 years and minimum of drought frequency occur in Abomoosa and Siri stations with 2 years.

Operator's participation in watershed management projects is essential and important in success of the project and Todays, participation in the world as the most efficient method known for watershed management. The main objective of the present research was to investigate the effects of economic, Political and social factors on people's participation in watershed management projects in the basin is meshkin chay in Meshginshahr city using regression analysis. Study population is included residing villagers in the meshkin chay basin in Meshginshahr city, and 160 villagers have been selected as research samples. Research method was based on field work using questionnaire and SPSS software was used for data analysis. The results of the Pearson correlation test, shows that participation of people in different stages of Watershed Management Projects with economic and social factors has a significant relation in 99 percent statistical level, and with political factors has a significant relation in 95 percent statistical level, with positive regression coefficients of 0.535, 0.207 and 0.162 respectively.

From the beginning of human life due to the need for water living, streams and waters are considered. For use of water resources, agriculture, urban and industrial centers, and general civilization formed near rivers. But with the rise of industry and technology, man has begun to destroy nature. In surface water due to population growth and the proliferation of pollution, quality of rivers and aquifers becomes more difficult every day. The spatial and temporal variations of water quality in rivers as the main source of surface water, always a challenge for managers and decision-makers in the area of water resources. In this study the water quality of the main branch in Jajrood River in Shemshak _ Darbandsar terms of agriculture and drinking consumption has been studied. 5 samples were taken from the source to the output Jirood village. The concentration of major anions and cations were measured according to standard methods. The chemical composition of the samples using the graphical diagrams Wilcox and Schoeller were analyzed. Based on the results obtained with samples drawn on charts Wilcox and Schoeller also became apparent that water drinking Jajrood generally not suitable for use, but considering the amount of salt and sodium content of the water river used for irrigation of agricultural land use.

Despite the relatively long history of erosion and sedimentation studies in Iran, a large difference between their estimates was found. In order to achieve a common view on the extent and rate of erosion and sediment production in the country, the following available data were analyzed: a) results of countrywide applications of erosion models, b) soil loss measurements in plots, c) erosion calculations based on CS-137, d) suspended load of rivers in gauging sites, e) bed load to suspended load ratio in selected reservoirs, and f) contribution of erosion features on sediment yield. Average rates of specific erosion and suspended sediment yield in Iran were obtained to be about two and six t.ha-1.y-1, respectively; which seems to be logical due to the dominance of dry climate in large parts of Iran. A few limited studies showed that the contribution of surface erosion (rill and interrill) on sediment is about 1/2 of other erosion features (gully, mass movements, river bank). Finally, it was shown that the specific rate of sediment yield is increased by an increase in basin area up to 10,000 km2 where it is followed by a downward trend in larger basins. Obviously, these estimates are relatively rough and there is still a long way to achieve more accurate estimations.

Studies of climate change impacts on future droughts can help programming for the management of water resource and adaptation of the destructive effects of this phenomenon. In this study was tried to assess the climate change in 2011-2030 period and its impact on drought in Plasjan basin. To achieve this purpose, after validating Lars-WG to generate weather parameters, HadCM3 output under A2 scenario downscaled. Next, minimum and maximum temperature and precipitation was predicted. Then SPI index was calculated. The results indicate increase of 7.2 percent in the average of annual precipitation. The most severe agricultural drought will occur in August and hydrological drought will fall out in December based on 6 and 12 months SPI respectively. The annual analysis showed that 75% of the years are in normal condition. Therefore, in Plasjan basin, increasing in droughts frequency will not be expected in 2020s.

Check dams are small structures that reduce slope of stream bed and mitigate flow velocity for an increase in time of concentration and change of flood hydrograph. About 70% of recent watershed management measures for erosion and flood control consisted of check dams’ construction. Considering different function of check dams in reducing discharge (increase in time of concentration), this research carried out to determine function of check dams for increase in time of concentration in three watersheds including Eqlid, Marvdasht and Mamasani in Fars Province. In this research, more than 1000 check dams were investigated in Tavileh-Band, Tange-Shoul, and Jonagan watersheds located in Eqlid, Marvdasht, and Mamasani regions, respectively. Time of concentration before and after Constructed check dams was measured in the field and by theoretical methods. The results of this research revealed that constructed check dams were able to increase time of concentration but this change was different in different areas of study. Increasing concentration in Eqlid watershed was more than watershed of Marvdasht and mamasani. The results of this research indicated that success of check dams for increase in time of concentration in watershed projects requires correct estimation of discharge, correct selection of critical stream, proper design of check dam dimension, considering optimum interval between check dams and management of check dams’ maintenance.

The influence of vast human activities had significant ecological problems on natural ecosystems. Woodcutting and destroying rangelands for rural, municipal and industrial development without considering their potential, caused land deterioration, decreasing vegetal cover and soil infiltration, lowering groundwater level, increasing flood volume and number, increasing agricultural drought, increasing landslides and soil erosion, decreasing land fertility and crop yield and increasing cropping expenses. Improper management of forest, range, agricultural and mining lands, neglecting water erosion control practices in road construction projects and facilitating sensitive lands to be eroded all cause accelerated erosion which destroy water, soil and financial resources.