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4.4 Interpretation and presentation of results
After the process of data acquisition and handling, it would be necessary to perform some interpretation of these data in order to provide a more readable information as well as to highlight the aspects that deserve a special attention but that could be hidden within the longer data report.
4.4.1 Presentation of results for technical purposes
It is difficult to provide guidelines for preparing the technical interpretation of results, because it will depend on the information obtained, the characteristics of the studied area and also on the experience of the team. Nevertheless, this report should cover the following issues:
• A short description of the knowledge of the erosion problems in the area before the implementation of the measuring programme, that justified the selection of this area for measuring.
• An assessment of the new qualitative and quantitative aspects of erosion processes learned during the Programme. Erosion and sediment yield rates for individual events or averaged for the year should be summarized here, together with some information on runoff coefficients and dissolved solids concentrations.
• An estimation of the reliability of the data obtained, with some discussion on the behaviour of sediment concentrations during the events, the similarity or differences among events, the seasonal patterns of erosion and sediment transporting events, and the representativeness of the events that occurred during the measuring period, looking to the long-term rates. The advantages or limitations of the measuring programme should be discussed here.
• Finally, an assessment of the relevance of the erosion and sediment yield rates measured with respect to the problems of land degradation, water quality deterioration and damages to hydraulic structures.
The implementation of an erosion measurement programme in an experimental area requires the involvement of a team of experts. An orientation about the composition and dedication of such a team is presented on the basis of the experience acquired in the three field sites during the implementation of the pilot project.
The instrumentation required will be also summarised and an indication of the instruments prices will be provided.
The following estimations about the necessary staff, time and equipment are made on the basis of the standard experimental site described in Chapter 3, and for a period of three years. This time is considered fit to the process of selection and installation of the experimental area, including a first year of full functioning and data acquisition, processing and implementation.
To facilitate the understanding, the instrumentation and other equipment aspects of the experimental area will be presented first, followed by the estimation of the required staff and an indication about the field visit programme.
The necessary equipment is composed of:
• the field instrumentation;
• the auxiliary equipment; and
• the laboratory for sample analysis.
Recommendations about the experimental area have been presented and can be summarised as: extension up to 20 km2, three or more catchments instrumented in the same experimental area, control of land use guaranteed in the mean-long term, easiest accessibility allowed by the experimental objectives, protection against natural hazards and vandalism, channel stability in the reach of measurement.
Field instrumentation, presented in detail in Chapter 3, is composed of:
• Runoff control structure. Flume or weir according the circumstances of bedload transport of the flow.
• Data logger. Two counting channels. Minimum autonomy of one month with a recording rate of 5 minute. Alkaline batteries with life longer than 12 months.
• Water level sensor. An electronic device to convert water level into an electronic impulse. Directly readable by the data logger. Capacitive sensor device is recommended for semi-arid conditions.
• Suspended sediment sampling instrument. Two simultaneous systems recommended: a) a programmable pumping water instrument triggered by the data logger or other water level threshold triggering mechanism, and able to output signals to the data logger to record the exact time of sampling; b) a siphon sampling device, consisting on a series of bottles at different heights, which takes water samples at various water levels as the hydrograph rises. This is to avoid the miss of the higher part of the hydrograph. The bottles are installed in a panel installed in a vertical of the flow.
• Rainfall recording stations. A minimum of one rain recorder per hydrometric station. Tipping bucket mechanism pluviometers connected to data logger and with 0.2 mm resolution, recommended.
The auxiliary equipment is listed in Chapter 3. From all the instruments and materials cited, the portable computer accounts for a good part of the cost. It is necessary to underline its features of reliability, robustness, autonomy and weight. A waterproof bag is an essential accessory as well as cables, plugs or specific interface devices for connection with the data logger and the required software for data transmission to the computer.
The laboratory equipment is also detailed in Chapter 3. To the cost of the listed material it is necessary to add the cost of the room and conventional facilities and services (water supply, electricity, maintenance, etc...) that is usually provided by the implementing agency.
The recommended staff necessary for the three years of implementation including one year of complete operation is composed of:
• Research leader responsible of the project. Experienced researcher in soils and surface hydrology. Provides design, direction and supervision of the project. Part time dedication to the project. 12 man/months.
• Research leader assistant. Experienced researcher in soils and/or surface hydrology. He or she is the executive researcher of the project, full time involvement. To be able to assume leadership if circumstances requires. 36 man/month.
• Two junior researchers. Post doctoral (Ph.D.) or pre-doctoral researchers on soil or hydrology. Responsible for performing the operation of the project under the direct supervision of the research assistant. Installation of facilities, instrumentation, data acquisition, process and interpretation. Operation of installations and maintenance. Laboratory analysis. 2 x 36 man/months
• Auxiliary (non technical) personnel. One field assistant, mainly for maintenance and custody of installations. Advisable with residence in the vicinity of the experimental area. 12 man/month. Secretary staff personnel mainly for document production, and general management assistance. 12 man/months.
The programme of visits is highly conditioned by the weather:
• one or two weekly visits in rainy weather for maintenance of samplers;
• one monthly visit for data recovering; and
• eventual visits during discharge events for direct sampling, maintenance and general operation supervision.
The financing of research initiatives on erosion measurement may arise from diverse sources according to the context of the specific research project. The primary source should be the budget for research at the national level. If a National Erosion Control Programme is set up, as advised, it should provide the adequate mechanisms to channel the required research funds.
International or supra-national organisations may play an important role in some cases. The Commission of the European Communities Research Programme provides substantial funds for research projects on the environment, amongst them erosion measurement projects are included. That funding is restricted to the member countries, but the Commission of the European Communities (CEC) has other programmes targeted to nonmember countries. In this context and particularly aimed to the cooperation with Mediterranean nonmember states, the MEDA programme should be underlined because of its importance and potential source of funding projects in diverse fields, among them the environmental cooperation (CEC, 1996).
The United Nations system traditionally provides funding opportunities for applied research projects in the field of earth sciences, agriculture, water resources, environmental protection, etc... There are several UN agencies involved, among them FAO, UNESCO, UNDP and UNEP should be quoted.