مجله ترویج و توسعه آبخیزداری
پیاپی 14 (پاییز 1395)

The quantity and quality of Zagros Forests (west Iran) are declining through improper management and land-use practices negatively affecting life in the regional scale. The objective of this research was explored the change in soil quality through conversion of forest to rain-fed practices which was conducted in the Gazaf-e-olya village in the Merek watershed, Kermanshah, Iran. Thirty five soil samples were collected from surface soil layers and subjected to soil physicochemical analysis. The data also were analyzed both classical and semivariance using SAS software. The results showed that there was no significant difference for soil particles distributions (sand, silt and clay) in the forest and rain-fed areas. The respective level of bulk density (BD) in the forest and rain-fed was 1.26 and 1.32 gr-1cm-3, indicating significant difference (p

Rainfall is of the most important elements in climatic studies and climate change is mainly due to changing precipitation amount. Therefore, rainfall is discussed in most climatic researches, especially those which are related to determining dry/wet periods. Anomalies of climate elements are of the main factors causing extreme events such as floods, droughts, desertification etc. in most parts of the world including Iran. Precipitation anomaly percent (PAP) is an important measure in drought assessment. Current study applies linear regression and Mann-Kendal tests on data from Chitgar synoptic weather station in order to determine the trend and change points in precipitation time series in Kan watershed during 1994-2014. Also moving average and anomalies for total annual precipitation and mean annual temperature were calculated and dry/wet years were recognized based on them. The results show that precipitation trend has been negative in Kan watershed, in general, during two recent decades, though it is not meaningful (in 5% significance). In addition, the investigations showed that the studied area has faced slight and average drought in 1990s, however after that, dry/wet years changed from year to year. Totally there was no severe and extreme drought in Kan watershed during two past decades, but it can be said that most years were considered as dry years during this period.

Climate change and temperature increase are of the important environmental issues for human. The temperature changes can help to monitor the climate change in a region. The researches done in all over the world show the gradual increase of the mean temperature. The observation of 8 synoptic stations in the statistical period of 1954-2014 were used to recognize the temporal changes of temperature extremes (minimum, maximum, and average) in southern provinces of Iran including Khouzestan, Hormozgan, Boushehr, and Sistan & Balouchestan. Liner regression and also non-parametric statistical method of Man- Kendal due to the non-linearity of climatic components were used to do the research. Statistical significance of two methods is nearly same. Based on the results, minimum, maximum, and average of temperature components have had a positive trend in the common statistical period in most of the cities, namely the temperature has increased and it only had a negative trend in most of the cases in Iranshahr city. Graphical test of Man-Kendal showed that all of the changes are in a positive direction and sometimes there is a sudden change into a decreasing direction.

It’s not possible to estimate flooding intense of sub-basin only by using existence data of hydrometric stations because of lack of hydrometric stations on sub-basin and also lack of recorded flood data. To estimate flooding intense, Karakhe’s watershed with 43 thousand km2 was selected. This watershed is located at Lorestan province, west southern part of Iran. Data from 11 hydrometric stations was used to investigate the reaction of sub-basin without recorded data. By using homogenous test, correcting errors or lacks and determining 57 years as common time base on SMADA software, the best statistic distribution model was log Pearson type 3. This distribution model was used to determine flooding coefficient and to calculate planed discharge values in the return periods. Results indicated that planed discharge values was equal to flooding coefficient (kt). Additionally, experiment formula of Dicken and Creager was used to estimate flooding coefficient and then the results was evaluated by calculated results derived from hydrometric stations. The results indicated that Dicken’s formula is more applicable. Values derived from Dicken’s formula are approximately to values with return periods of 2, 5, 10, 20, 25 and 50 years and differences was not significance. Coefficients of experimental formula was also calibrated for the study area and then it is possible to calculate maximum momentous discharge on the sub-basin and used on the ongoing projects.

Investigation the public participation in changing of cropping pattern is an important role to success of the soil and water projects. But, participation of people with the executive departments is difficult process. This study set out with the aim of investigation the public participation in changing of cropping pattern with the field study and survey questionnaire in Ali-Abad region of Golestan province. In this study, 86 beneficiaries from a population of 110 farmers were chosen in the case study using Cochran approach and verbal interviews were done. Results indicated that five factors consist of the “economic prosperity, automating the traditional activities, ensuring children's future, the water rising of wells, and sufficient knowledge of the project” are top priorities for farmers respectively. Also these factors such as “projects profitability in the future, integrating lands, conflicts between people, improve the soil and the visit of the project by farmers” are the final priorities. Finally, in order to develop modern agriculture, the executive organs have been offered to focus their attention on agronomist priorities that is often related to economic issues.

Nowadays, numerous risks seriously threat the health of watershed ecosystems. Human driven modifications of the Earth's natural environment largely affect ecosystem structure and functions. Therefore, assessment of the relative condition of watersheds is essential to plan appropriate management practices. In this regards, various approaches such as reliability-resilience-vulnerability (RRV) indicator based and conceptual model have been proposed. Assessment and monitoring ecosystem health using a promising approach of the RRV model to ascertaining watershed health provides early warnings of environmental degradation causes. So, watershed ecosystems health assessment is a fundamental and an essential step to ecological services conservation. To apply the RRV model, several criteria have been used within a riskbased standpoint. Although, the application of the RRV model has been commonplace for years in various ecosystems, but, the use of the RRV indicators in watershed health assessment has been rarely reported. Towards this, the present research was conducted to introduce, to explain the application and to review the literatures of the RRV model. The results of the literature review indicated that more studies have been limited mostly to reservoir operations management. While, the recent studies have focused on health assessment of the different ecosystems such as stream, urban and even watershed ecosystems. Based on these researches, the application of the RRV model has been suggested as a prerequisite for appropriate and integrated watershed health assessment.

Gully erosion is a form of soil erosion by water and it is one of the important processes of land degradation in Iran is important processes which occurs under particular environmental conditions. This type of the erosion caused extensive destruction of the land due to the relatively large size, rapid development and production of sediments. Generally, contributing factors of gully are divided into two categories natural and human. Natural factors include maternal materials sensitivity to erosion, high erodibility of the soil, hydrological conditions, the volume and speed of basin runoff, floods and rodent activity, and in human factors are such as land uses, unprincipled irrigating of land and destruction of vegetation. It is necessary presenting of strategies for conflict with this problem after studying the formation mechanism influencing factors. In order to understanding of various aspects of combating with this phenomenon in Aro basin, located in the Firoozkooh city, overview is done and after determining the types of erosion and sediment yield, the parameters of lithology, slope, soil and land cover as some of the important influencing factors the types of erosion, especially gullies, were studied. Overall, causing factors of gullies are affected by the geology, tectonic, climatic, edaphic, topographic and human activities in this area. These gullies are caused by natural factors and have been expanding by human intervention. Therefore, management must consider all the necessary factors to harnessing them, because history has shown that successful will not be followed with one-dimensional approach.