Abstract: The increasing competition among the limited land and water resources leads to the development, monitoring and evaluation of these resources in irrigated agriculture. The objectives of this study were to make cross-system comparison and comparative performance analysis of irrigation schemes based on the system type, climate and management type using the International Water Management Institute (IWMI)’s six performance indicators for the year 2001. Statistical analyses were conducted to determine if statistically significant difference existed between the system types, climatic conditions and management types for each and all of six indicators. ANOVA test results indicated that statistically significant difference at p=0.05 level (p<0.05) was determined between the system types, climates and management types for most of six indicators. In addition, the differences between the system types and climates for all of six indicators were statistically significant, whereas the difference between the management types was not. The mean values of the pumping in system type and semi-humid in climatic conditions were higher than that of the others, whereas no clear difference in the means of the management types was determined. Although more water than the requirement was used for all schemes, water was not used efficiently possibly due to inappropriate crop pattern and intensity, irrigation infrastructure, reliability of the data, education level of the managers and farmers and structure of the administration.
INTRODUCTION
The increasing competition among the limited land and water resources leads to the development, monitoring and evaluation of these resources in irrigated agriculture. The information on irrigation water management in a detailed scale like in country level is not common due to the lack of data, or reliability and accessibility of the data. The evaluation of irrigation water use efficiency has been concern of many researchers (Bos and Nugteren, 1974; Levine, 1982; Bos et al., 1994; Molden et al., 1998), but the performance of irrigated agriculture with limited land and water resources has not been satisfactorily monitored and evaluated because we have not been able to compare irrigation systems relative to each other (Sakthivadivel et al., 1999). Therefore, assessing the performance of irrigated agriculture is necessary in order to evaluate the impact of agricultural and hydrological interventions.
The performance of irrigation schemes is evaluated for a variety of reasons such as improving system operations, assessing progress against strategic goals, assessing the general health of a system, assessing impacts of interferences, diagnosing restrictions and comparing the performance of a system with others or with the same system over time (Molden et al., 1998).
The comparative performance indicators allow for comparison between countries and regions, different infrastructures (fixed or flexible), system (diversion or pumping) and management (agency, farmer, or joint) types, distribution procedures (supply versus demand), climatic conditions (wet or dry) and performance assessment of a specific project over time because they consider common elements to all systems (Molden et al., 1998).
Using the comparative performance indicators developed by the International Water Management Institute (IWMI), the performances of irrigation schemes of 13 Water User Associations (WUAs)-operated (Çakmak, 1997) and 213 public-operated in 21 different regions in the city of Konya (Beyribey, 1997), Bursa-Uluabat (Değirmenci, 2001a), 158 WUAs-operated (Değirmenci, 2001b), 7 WUAs-operated in Konya (Çakmak, 2001), Sakarya Basin (Çakmak and Beyribey, 2003) were evaluated in Turkey. Molden et al. (1998) assessed the performance of 18 irrigation schemes in 11 different countries using 9 external comparative indicators developed by the IWMI. Sakthivadivel et al. (1999) demonstrated four typical applications of these indicators; cross-system comparison, temporal variations in performance at one system, spatial variations within one system and comparing performance by system type to 40 irrigation schemes from 13 countries.
A number of researchers have evaluated the performance of particular irrigation systems with various indicators (Abernethy, 1986; Seckler et al., 1988; Molden and Gates, 1990; Sakthivadivel et al., 1993; Sarma and Rao, 1997; Molden et al., 1998; Bandara, 2003). The performance of the irrigation systems depends upon several factors such as infrastructure design, system and management types, climatic conditions, price, availability of inputs and socioeconomic conditions (Sakthivadivel et al., 1999). However, in most of these studies, the performances of schemes were evaluated using the limited number of these parameters (factors). In addition, the comparative performance indicators were applied to an individual or regional schemes, or schemes from several countries. Extensive assessment of all schemes in a country using all these parameters helps the managers and researchers to better compare them and develop sound management tools.
Therefore, the objectives of this study are to make: a) cross-system comparison of all irrigation schemes in Turkey, b) comparison of the schemes based on the system type, c) comparison of the schemes based on the climatic conditions and d) comparison of the schemes based on the management type using the IWMI’s six performance indicators for the year 2001. To achieve the objectives, we compiled a large data set that compromise of water supply, crop types, crop water requirement and irrigated and command areas from the evaluation report of the Irrigation Schemes operated by SHW and transferred refer to the state Hydraulic works and the schemes transferred to the WUAs, respectively. Whereas the data of crop pattern and unit yield and price was obtained from the Product Count Result Reports of the Irrigation Schemes operated by SHW and transferred refer to the state Hydraulic works and the schemes transferred to the WUAs, respectively (Anonymous, 2001a and 2001b). SHW and transferred refer to the state Hydraulic works and the schemes transferred to the WUAs, respectively. This data set was then used to calculate six irrigation performance indicators: Output per unit command, output per unit cropped area, output per unit water supply, output per unit water consumed, irrigation intensity and relative water supply.
MATERIALS AND METHODS
The study area: Irrigation schemes in this study were developed and operated by the General Directorate of the SHW, but the transfer of the schemes to the WUAs started in 1992. The total of 239 schemes (57 and 182 were operated by the SHW and WUAs, respectively) was evaluated in this study. The locations of the studied irrigation schemes are presented on the map of Turkey in Fig. 1.
Land, water, climate and crop resources of the study area: The total, arable, irrigable and economically irrigable land in Turkey are 78, 28.05, 25.82 and 8.50 million ha, respectively. Approximately 50% (4.5 million ha) of the economically irrigable land has already been developed. The irrigation areas developed by the SHW, GDRS (General Directorate of Rural Services) and farmers are about 50, 27.7 and 22.3%, respectively, (Tekinel, 2001).
The total potential water is 186 billion m3 in 26 drainage basins in Turkey and 95 billion m3 of this amount is usable. However, the total surface and groundwater which is consumable technically and economically is 110 billion m3. Ninety five, 3 and 12 billion m3 of this amount are provided by the rivers emerged in the country; the rivers emerged out of the country and groundwater, respectively (Çakmak and Beyribey, 2003).
Turkey is located in a sub-tropical region and mainly under semi-humid and semi-arid climate. The ranges of the annual mean temperature are 18-20, 14-15 and 4-19°C in the southern, western and middle and eastern part of the country, respectively. In general, summer is warm and dry, whereas winter is cold and rainy (Degirmenci, 1996). The annual mean precipitation, total precipitation, total runoff and total usable potential are 643 mm, 501 km3, 186 km3 and 110 km3, respectively (Tekinel, 2001).
| Fig. 1: | Map of Turkey showing the locations of the SHW (flag) and WUAs (triangle)-operated irrigation schemes. There is more than one scheme in each marked point |
A variety of crops are grown in the study area, but common ones are wheat, sugar beet, fruit, vegetable, corn, cotton, tobacco and olive.
Performance indicators: Six external indicators developed by the IWMI were used for the comparative performance evaluation of the 239 irrigation schemes (Eqs. 1-6). The first four indicators relate the output (crop production) to unit land and water. These indicators allow to comparing the performance of fundamentally different systems by standardizing the gross value of agricultural production. In the areas where water is scarce, the Standardized Gross Value of Production (SGVP) per unit water consumed is especially significant, whereas in the areas in which the land is the limited source, output per unit of command or cropped area is more important. The relative water supply was presented by Levine (1982) and expressed as the ratio of the total water supply to the total crop-water demand. These indicators can be calculated as (Molden et al., 1998):
| (1) |
| (2) |
| (3) |
| (4) |
| (5) |
| (6) |
where, SGVP is the output of the irrigated area in terms of gross or net value of production measured at local or world prices, irrigated cropped area is the sum of the areas under crops during the time period of analysis, command area is the nominal or design area to be irrigated, diverted irrigation supply is the volume of surface irrigation water diverted to the command area, plus net removals from groundwater, volume of water consumed by ET is the actual evapotranspiration of crops and total water supply is the surface diversions plus net groundwater draft plus rainfall.
The SGVP was developed for cross-system comparisons regardless where they are or what kind of crops is grown. It can be calculated as (Molden et al., 1998):
| (7) |
where Ai is the area cropped with crop I (ha), Yi is the yield of crop I (kg da-1), Pi is the local price of crop I ($ kg-1), Pb is the local price of the base crop (the predominant locally grown, internationally-traded crop) ($ kg-1) and Pworld is the value of the base crop traded at world prices ($ kg-1). Wheat was considered as the base crop because it was predominant locally grown and internationally traded.
The data on water supply, crop water requirement and irrigated and command areas for the schemes was obtained from the Irrigation Project Evaluation Reports, whereas the data of crop pattern and unit yield and price was obtained from Product Count Result Reports of the irrigation schemes operated by SHW and transferred (Anonymous, 2001a and 2001b).
Analysis of the data: Descriptive statistical parameters such as minimum, maximum, mean, plus and minus standard deviations were calculated for each of six indicators of system type, climatic conditions and management type. In addition, the analysis of variance (ANOVA) test was made using SPSS software (Norusis, 1990) to determine if statistically significant difference existed between the system types, climatic conditions and management types for each and all of six indicators.
RESULTS AND DISCUSSION
Cross-system comparison
SGVP per unit command: The minimum, maximum and mean values of the SGVP per unit command are 16, 9078 and US$ 1134, respectively (Table 1). The systems with the low values (less than $ 2000 ha-1) are those that mostly grow crops such as cereals with small area and low yield and local price. The systems with the high values ($ 2000 and greater) include orchards, industrial crops (sugarbeet, cotton and sunflower) and some cereals. The vast majority of the scheme which have high values of the SGVP per unit command are operated by the WUAs. These results indicate that the reasons for the high SGVP per unit command are the cropping pattern and intensity and the WUAs are successful in managing this. Molden et al. (1998) also investigated that the systems including orchards, industrial crops and some cereals had the high values of the SGVP per unit command. The SGVP per unit command was determined as in the range of 1070-1583, 144-8349, 679-2888, 2629, 67-2001, 1840, 195-5391 and 477-3626 US$ ha-1 in the studies of Değirmenci (2001a), Değirmenci (2001b), Molden et al. (1998), Yazgan and Degirmenci (2002), Çakmak and Beyribey (2003), Kloezen and Garces-Restrepo (1998), Çakmak (2001) and Sakthivadivel et al. (1999), respectively.
SGVP per unit cropped land: The minimum, maximum and mean values of the SGVP per unit cropped land are 65, 9763 and US$ 2250, respectively (Table 1). The SGVP per unit cropped land can be divided into two classes of irrigation systems. Irrigation systems producing cereals have the SGVP per unit cropped land around or less than $ 3500, whereas the systems producing non-cereal crops such as orchards, industrial crops (sugarbeet, cotton and sunflower) have the SGVP per unit cropped land between US$ 3500 and $ 10000. Therefore, non-cereal irrigation systems produce more value than the cereal irrigation systems by 0-300%. Most of the schemes with high SGVP per unit cropped area are operated by the WUAs. The SGVP per unit cropped land was found as in the range of 2857-4415, 190-14843, 2900-4000, 105-1800, 4198, 354-8659, 1317-2585, 359-6197, 384-3626 and 384-3434 US$ ha-1 in the studies of Değirmenci (2001a), Değirmenci (2001b), Molden et al. (1998), Kloezen and Garces-Restrepo (1998), Yazgan and Degirmenci (2002), Çakmak and Beyribey (2003), Girgin et al. (1999), Çakmak (2001) and Sakthivadivel et al. (1999), respectively.
SGVP per unit irrigation supply: The range and mean of the SGVP per unit irrigation supply are 0.01-1.79 and 0.27 US$ m-3, respectively (Table 1). Cereal-producing systems give a gross value of output per unit volume of irrigation water varying between $ 0.01 and $ 0.4. However, systems growing orchards, industrial crops (sugarbeet, cotton and sunflower), vegetables and some cereals produce a SGVP per unit volume of irrigation water between $ 0.4 and $ 1.8. The SGVP per unit volume of irrigation water is higher in semi-humid regions where irrigation requirement is generally lower. In addition, the vast majority of the schemes with high SGVP per unit irrigation supply are operated by the WUAs. These results indicate that the reasons for the high SGVP per unit irrigation supply are the cropping pattern and intensity, climatic conditions and management type. The SGVP per unit irrigation supply was calculated as in the range of 0.31-0.50, 0.02-1.84, 0.04-0.63, 0.00-0.16, 0.11-0.12, 0.02-0.67, 0.18-0.41, 0.02-1.29 and 0.04-0.63 US$ m-3 in the studies of Değirmenci (2001a), Değirmenci (2001b), Molden et al. (1998), Kloezen and Garces-Restrepo (1998), Vermillion and Garces-Restrepo (1996), Çakmak and Beyribey (2003), Girgin et al. (1999), Çakmak (2001) and Sakthivadivel et al. (1999), respectively.
SGVP per unit water consumed: The range and mean of the SGVP per unit water consumed are 0.01-2.66 and 0.55 US$ m-3, respectively (Table 1). The SGVP per unit water consumed can also be grouped into two main classes. Cereal-based systems give a gross value of output per unit water consumed varying between $ 0.01 and $ 0.7. However, systems growing orchards, industrial crops (sugarbeet, cotton and sunflower) and vegetables produce a SGVP per unit water consumed between $ 0.7 and $ 2.66. The SGVP per unit volume of irrigation water is higher in the schemes located in the semi-humid regions and operated by the WUAs. These results indicate that the reasons for the high SGVP per unit irrigation supply are the cropping pattern and intensity, climatic conditions and management type. The SGVP per unit water consumed was determined as 0.58-1.09, 0.04-3.02, 0.03-0.91, 0.00-0.41, 0.08-2.54, 0.17-0.35, 0.07-2.25 and 0.05-0.62 US$ m-3 in the studies of Değirmenci (2001a), Değirmenci (2001b), Molden et al. (1998), Kloezen and Garces-Restrepo (1998), Çakmak and Beyribey (2003), Girgin et al. (1999), Çakmak (2001) and Sakthivadivel et al. (1999), respectively.
Irrigation intensity: The range and mean of the irrigation intensity are 1-157 and 49%, respectively (Table 1). Majority of the schemes have irrigation intensity between 20 and 90%, but the mean intensity of WUAs-operated schemes is higher than that of the SHW-operated schemes. This indicates that the WUAs are successful in irrigation of the projected area. The most important reason of the low irrigation intensity might be the lack of infrastructure, water and operation and maintenance activities, water delivery, irrigation method and not making irrigation because of enough precipitation in the related year. The irrigation intensity was found as 32-117, 4-100, 44-100, 24-105, 57-81, 15-94, 36-104 and 25-96% in the studies of Erözel and Alibiglouei (1991), Değirmenci (2001b), Beyribey et al. (1997a), Beyribey et al. (1997b), Yazgan and Degirmenci (2002), Çakmak and Beyribey (2003) and Çakmak (2001) and Değirmenci and Yazgan (2002), respectively.
Relative water supply: The minimum, maximum and mean of the relative water supply are 0.19, 9.76 and 2.66, respectively (Table 1). The relative water supply indicates how well irrigation supply and demand are matched, a value over one would suggest too much water is being supplied, possibly causing water-logging and negatively impacting yields; a value less than one indicates that crops are not getting enough water.
| Table 1: | The output per unit cropped area, command area, irrigation supply and water consumed; irrigation intensity; and relative water supply |
Column 1: System name, Column 2: Type of system (D and P is the diversion and pumping), Column 3: Climate (SH: Semi-humid, SA: Semi-arid, H: Humid), Column 4: Type of management (SHW and WUAs are the schemes operated by the State Hydraulic Work department and Water User Associations) Column 5: Output per unit cropped area, US$ha–1, Column 6: Output per unit command area, US$ha–1, Column 7: Output per unit irrigation supply, US$m–3 Column 8: Output per unit water consumed, US$ mG3, Column 9: Irrigation intensity, %, Column 10: Relative water supply | |
The optimum value of the relative water supply is one.
The irrigation water less than the requirement is applied to 11 schemes in which 10 and 1 are operated by the WUAs and SHW, respectively; whereas 228 schemes receive water more than the requirement. This indicates that irrigation water is not used uniformly and efficiently by both management types. Levine (1982) stated that water supplied more than 2.5 times of the net requirement was an indication of inappropriate water management. Since planned water delivery is not available in the irrigation schemes, the large amount of water in the canal is wasted; as a result, this increases the relative water supply. The relative water supply was determined as 1.20-1.48, 0.91-7.15, 0.60-1.79, 0.58-2.41, 0.80-4.10, 0.60-1.09, 1.30-8.40, 1.40-1.80, 0.30-7.83 and 1.88 in the studies of Değirmenci (2001a), Değirmenci (2001b), Beyribey et al. (1997a), Beyribey et al. (1997b), Molden et al. (1998), Yazgan and Degirmenci (2002), Çakmak and Beyribey (2003), Vermillion and Garces-Restrepo (1996), Çakmak (2001) and Bandara (2003), respectively.
| Table 2: | Descriptive statistics and ANOVA test result |
| aDiversion,bPumping, cDiversion and pumping, dThe number of samples (irrigation scheme), Note: Anova test results for the six parameters of the system type is F(2,1437)=3.500, P=0.030 Anova test results for the six parameters of the climate is F(1,1366)=13.135, P=0.000 Anova test results for the six parameters of the management type is F(1,1432)=0.334, P=0.563 |
|
Comparing performance by system type: The irrigation schemes were disaggregated based on the system types as diversion, pumping and diversion and pumping for each of six indicators and statistical analysis results are displayed in Table 2. Although statistically no significant difference at p=0.05 level (p>0.05) was determined among the system types for the output per unit water, irrigation intensity and relative water supply; significant difference was determined among them for the output per unit land and all of six indicators. The pumping and diversion have the highest and lowest mean values for the output per unit land and water. The reason might be due to the fact that people are using water more efficiently because pumping water from river or storage is costly compared to the other systems.
Comparing performance by climate: Drought indices were determined for irrigation schemes using De Morttonne Drought Indices. Turkey is mainly under the two indices; semi-humid and semi-arid. The irrigation schemes were grouped based on the climate as semi-humid and semi-arid for each of six indicators and statistical analysis results are displayed in Table 2. Although statistically no significant difference at p=0.05 level (p>0.05) was determined between the climatic conditions for irrigation intensity and relative water supply, the difference was significant for the output per unit land and water and all of six indicators. The means of all indicators were higher in semi-humid regions than in semi-arid regions. The reason might be due to the fact that irrigation requirement is generally lower in semi-humid regions compared to the semi-arid regions.
Comparing performance by management type: The irrigation schemes were grouped based on the management type as the SHW and WUAs-operated for each of six indicators and statistical analysis results are displayed in Table 2. Statistically no significant difference at p=0.05 level (p>0.05) was determined between the management types for output per unit land, output per unit water supplied and all of six indicators except the output per unit water consumed, irrigation intensity and relative water supply. Although there is statistically no clear difference in the means of the management types for the output per unit land and water, more of the designed area is irrigated by the WUAs with efficient use of water, where irrigation intensity is larger and relative water supply is lower.
In this study, cross-system comparison of all irrigation schemes developed by the SHW department and comparative performance analyses of the schemes based on the system type, climate and management type were made using the IWMI’s six performance indicators for the year 2001.
The output per unit land and water can be grouped into two main classes. The systems that mostly grow orchards, industrial crops and some cereals have higher output per land and water than the cereal-producing systems. Although more water than the requirement is used for all schemes, water is not used efficiently because output or production per unit land and water is relatively low. This might be due to the application of inappropriate crop pattern and intensity to the project areas, the lack of infrastructure and the lack of the knowledge and experience of the farmers for an appropriate irrigation practice.
Irrigation schemes should be grouped and evaluated based on their crop patterns and growth-time and marketing situation and then similar schemes should be compared or evaluated among themselves to expand this topological study. In addition, time-series of topological study can be conducted to better understand key determinants of performance.