The materials that we used as part of this study are the study site, the data collection tools in the field and finally the tools for analyzing and processing this data.

Konni irrigated perimeter

The Konni perimeter is split into Konni 1 and Konni 2, each managed by a cooperative. The Konni 1 perimeter with an area of 1012 ha brings together 15 Mutualist Producer Groups (GMP). The perimeter of Konni 2 covers an area of 1440 ha and is made up of 19 Mutualist Producer Groups. The 34 GMP became 23 hydraulic sectors as part of the reform of cooperatives and ONAHA, which led to the creation of the Association of Irrigation Water Users (AUEI).

The area is used by 3150 families from 12 villages and there are more than 4000 heads of families who operate this hydro-agricultural development in Konni. It is fed by the Maggia, a river which flows only in the rainy season, two earthen dams Zongo and Mozagué having respectively a capacity of 12 and 30 million m3 at creation. These two dams supply a buffer reservoir in Tcherassa via a 15 km long supply canal. Figure 1 illustrates the geographical location of the Konni perimeter with its related infrastructure.

The methodology that we adopted is summarized in two steps (2):

Good management of an irrigated area requires a diagnostic approach. With some differences, the same methodological approach is applied to all the sites selected for this diagnosis. It is based on the “Participatory Diagnosis and Planning of actions to improve the performance of irrigated areas (DPRP)” method developed by IWMI and ARID [7] . It is an approach which seeks, in collaboration with farmers, to analyze the performance of their irrigated system. It makes it possible to diagnose the main constraints and then produce an action plan with a view to improving the system. In this study, we used the DPRP method in half for all stakeholders, that is to say we only carried out a diagnosis of hydraulic infrastructure.

To achieve the objectives set for this study, it is essential to adopt an appropriate methodology. The methodology adopted is presented in three (3) essential stages which are: site visit, documentary research, field work.

Step 1: Visit the site

The visit is organized for reconnaissance of the site, contacting irrigators, technicians and informing them of our upcoming visits. This first phase aims to justify our visit and obtain general information on the area.

Step 2: Documentary research

As knowledge can never be based on a single source and the information is scattered and sometimes contradictory, it is imperative for us to consult the documents relating to the Konni irrigated area from the competent institution which is the ONAHA (National Office for Hydro-Agricultural Developments) documentaries.

Step 3: This is a set of semi-directives, qualitative interviews with the cooperative, the Director of the perimeter and the operators to collect information on the physical state of the Hydraulic infrastructures at the level of the study perimeter;

In terms of the data collection method, taking into account the different groups of stakeholders involved, the following tools were used:

Step 4: Field work

Physical observation consisted of exploring the perimeter to note the physical state of the plots and hydraulic infrastructures. At the end of this observation, a comparison of ideas is made with the aim of correcting certain erroneous information that was given during the interviews.

An interview guide adapted to each type of actor has been developed. The idea is not to fill a questionnaire, but to let the interlocutor express themselves freely, starting with a historical overview, while subsequently asking for clarification on certain points.

a) Dam of Mozagué

Bathymetric measurements showed that the volume of sediment that accumulated in the Mozagué dam reservoir is 9.77 million m3, which reduces its initial capacity from 30 million m3 to 20.2 million m3 after 35 years of service.

b) Dam of Zongo

Bathymetric measurements showed that the volume of sediment that accumulated in the Zongo Dam reservoir is 1.2 million m3, which reduces its initial capacity from 12 million m3 to 10.8 million m3 after 41 years of service.

c) Tcherassa reservoir

Initially, in its normal filled state, the Buffer reservoir has a useful volume of 1.2 million m3. Bathymetric and topographical surveys carried out by [7] show that the current useful volume is 1.05 million m³, i.e. a reduction in its capacity of around 150 thousand m³ compared to the initial state. The total volume of siltation corresponds to the volume of the dead section to which we add the current siltation, i.e. a volume of 0.42 million m³.

a) Feed channel

Water is conducted from the Zongo dam spillway to the irrigated area by a 15 km long intake canal. The investigation carried out during the first phase of the study showed that the cracked panels of the intake channel have one or more cracks. These cracked panels represent significant water leak points even if the length and thickness of the crack is minimal. The expansion joints are all in poor condition. Their complete replacement is necessary. Panel cracks.

b) Dead Head Channel

The canal has horizontal and vertical cracks along its entire length apart from a few panels. All joints are in poor condition. The panels of average length of 2m are either cracked or grassed. 40 panels have a continuous horizontal crack demonstrating a general subsidence of this section. The berms are bare. This channel must be completely rebuilt in reinforced concrete.

The greatest stress observed on all channels is the presence of longitudinal and transverse cracks in the covering panels. Also, it was noted that all the channels are unreinforced and cast in place.

Generally speaking, these structures present visible structural disorders and in particular:

a) Primary Channel A

This canal extends over a length of 11,500 ml distributed over three sections:

The results of the diagnosis give: 2843 degraded panels (i.e. 96%), only 14 panels have repairable cracks and the rest (175 panels) are in good condition.

The diagnosis identified 39% of cracked panels, 3.6% of panels in good condition and 57.4% of degraded panels.

b) Primary Channel B

This channel extends over a length of 7,275 ml. In its part located between the PA and the RN1, this canal is in poor condition.

The summary status of the diagnosis of the entire PB channel gives:

c) Primary Channel D

The diagnostic result gives:

d) Canal Principal C

The PC canal with a length of 2990 m presents the following failures over its entire length:

Plates in good condition concern plates 1m long. As soon as the length of the plates exceeds 2 m, cracks are apparent in the majority of the plates and the degradation of the plates intensifies. Photo 1 shows the condition of the secondary canals before the rehabilitation activities ( Figure 2 ).

The diagnosis of the tertiary canal network gave the following results:

Sprinklers

The diagnosis of the watering channels of the second phase shows that these channels, executed in compacted fill, have disappeared. They were replaced by channels maintained by farmers. These channels are grassy, with degraded banks, many termite mounds are found in the area of these channels and also trees and shrubs.

At the end of each sprinkler there is a discharge facility into the nearest colature. These masonry structures are all degraded and broken and are no longer functional.

The diagnosis of this equipment shows a large number of mask modules presenting a sealing problem with often significant water leaks.

Work of Dalot Crossed by a Kori

All structures are blocked between the RN1 and the Zongo dam. This is due to the lack of maintenance and cleaning of these structures. Due to the difficulty of access and the growth of thorny trees and shrubs around these structures, these hydraulic structures do not work well.

Inverted Siphon

The structure of the Civil Engineering parts of this work is in a stable state. No protection device is installed at the entrance to the siphon (grid), which encourages the accumulation of large waste at the entrance to the structure and thus blocks the flow. This sometimes encourages water to overflow upstream of the structure.

The secondary and primary colatures have a total length of 56751m. There are 7 primary colatures (A, B, C, D, J, K and L). The general condition of the colatures is:

The lack of maintenance of these colatures has made their operation impossible in some places. Rainwater follows the tracks all around and favors the gullying of the tracks and the banks of the colatures.

The diagnosis carried out during the first phase of the study shows the following state of the dikes:

The results of this study show that before the rehabilitation activities, the water mobilization works of the Mozagué and Zongo dams, the Tcherassa buffer reserve are faced with the problems of silting, aging of the basic materials and the lack of maintenance which reduced the operation of the perimeter and the performance of the irrigation system. These results are consistent with those obtained by [9] who affirms that the reduction in performance of the Konni irrigated area would probably be due on the one hand to the siltation of the two dams (Zongo and Mozagué) and the Tampon de Tcherassa reserve and on the other hand, the reduction in the number of irrigation could come from the significant infiltration at the Zongo dam which caused the significant infiltration at the basin level of the said dam and that the Mozagué dam was created. Concerning water transport and distribution structures, we note an advanced deterioration of hydraulic structures presenting enormous cracks on almost all of these structures. The same goes for the transport network and the irrigation canals which are in a poor structural state, visible and often widespread, with longitudinal and transverse cracks. This leads to leaks due to lack of maintenance and especially the aging of these structures. These results are consistent with the work of [10] on the irrigated area of Galmi, who stated that the degradation of the hydraulic infrastructure of this development is due to the lack of maintenance and their dilapidation. These results are also not far from those obtained by [11] on the Daibery perimeter where he showed that the main channels are cracked, invaded by plants, damaged jumpers and defective seals due to the aging of this arrangement. But the cracking observed and the defective seals are the most recurring problems on the main channels. Our results are consistent with those obtained here also by [12] who pointed out that the degradation of primary and secondary canals derives from the main problem of aging of hydraulic structures. Thus, as reported by [13] in his diagnostic study of hydraulic structures in an irrigated area of Djirataoua which revealed that the water transport and distribution structures are in a state of aging with a high level of degradation. This could be due to the age of the hydraulic infrastructure.

Indeed, when the perimeter is created, a significant volume of water supplies all of the plots. Based on the observation of the current seriously degraded state of the hydraulic works in the area of Djirataoua, there is undoubtedly a real problem of maintenance or even renewal of these works. However, the observation is the same as [14] , who noted that all of the structures are in a state of aging with a high level of degradation. Indeed, although these areas do not have the same characteristics of the irrigation system, we encounter the same constraints there.