Madagascar

Two major basin groups can be distinguished in Madagascar: the one draining to the west to the Madagascar Channel and the one draining to the east to the Indian Ocean. Rainfall in Madagascar varies from that of tropical rain forest to near desert conditions. The types of irrigation vary according to the three main ecological regions of the country: the Highlands, the West and the narrow East Coast. Because of the high altitude, in the Highlands the dry season (June-October) is cool, which limits crop production. The West is hot and the dry season is very long, up to nine months in the far south-west. Rainfall can be less than 400 mm/year. The East Coast is warm and humid with rainfall that can exceed 3000 mm/year and with almost no dry season. Irrigation potential has been estimated at 1.5 million hectares and over 70% of this area already benefits from irrigation, although large areas need rehabilitation.

TABLE 85 Madagascar: irrigation potential, water requirements and areas under irrigation

Country	Irrigation potential (ha)	Gross potential irrigation water requirement		Area under irrigation (ha)
		per ha (m³/ha per year)	total (km³/year)
West	1000000	16000	16.000	700000
East	500000	14500	7.250	387000
For Madagascar	1500000		23.250	1087000

The renewable water resources are estimated at 337 km³/year, which is almost 15 times the total water required for the development of the irrigation potential.

Islands

Five countries are grouped in this category, as shown in Table 86.

Cape Verde, an island group in the Atlantic Ocean to the west of northern Africa, is a very dry country. The islands of São Tome and Principe are situated in the Gulf of Guinea with very high rainfall. The three other countries are situated in the Indian Ocean to the east of southern Africa. Rainfall varies from an average of 900 in Comoros to almost 2200 mm/year in Mauritius. Table 87 summarizes the figures on irrigation and water requirements.

TABLE 86 Islands: areas and rainfall by country

Country	Total area of the country (km²)	Average annual rainfall in the basin area (mm)
		min.	max.	mean
Cape Verde	4030	60	500	230
Comoros	1861			900
Mauritius	2040	700	4000	2180
Sao Tome & Principe	960	900	7000	3200
Seychelles	455	1290	2370	1740
Total for islands	9346

TABLE 87 Islands: irrigation potential, water requirements and areas under irrigation

Country	Irrigation potential (ha)	Gross potential irrigation water requirement		Area under irrigation (ha)
		per ha (m³/ha per year)	total (km³/year)
Cape Verde	2990	25000	0.075	2779
Comoros	300	5000	0.002	130
Mauritius	20000	5000	0.100	17500
Sao Tome & Principe	10700	12500	0.134	9700
Seychelles	1000	5000	0.005
Total for islands	34990		0.315	30109

Data quality assessment

Over 1000 references have been consulted, of which about 25% contained information that proved to be more or less useful for the purpose of this study, although there is a large variation in the reliability of the information. Table 88 below shows the availability of information on water resources and irrigation potential by country. The first category refers to countries for which reasonably detailed information was available on both water resources and irrigation potential. The second category refers to countries for which either less detailed information was available for both water resources and irrigation potential or reasonable detailed information for one of the two subjects and less for the other. The third category refers to countries for which little information was available on both water resources and irrigation potential.

TABLE 88 Availability of information on water resources and/or irrigation potential by country

Category	Information on water resources and irrigation potential	Countries	Number of countries	% of total number of countries	% of irrigation potential
1	Reasonably detailed	Botswana, Burkina Faso, Cape Verde, Egypt, Kenya, Malawi, Mali, Morocco, Niger, Nigeria, Senegal, South Africa, Swaziland, Tunisia, Zambia, Zimbabwe	16	30	28
2	Less detailed	Algeria, Benin, Chad, Ethiopia, Guinea Bissau, Libya, Madagascar, Mauritania, Mozambique, Namibia, Somalia, Sudan, Tanzania	13	25	31
3	Little information	Angola, Burundi, Cameroon, Central African Republic, Comoros, Congo, Côte d'Ivoire, Djibouti, Equatorial Guinea. Eritrea, Gabon, Gambia, Ghana, Guinea, Lesotho, Liberia, Mauritius, Rwanda, São Tome and Principe, Seychelles, Sierra Leone, Togo, Uganda, Zaire	24	45	41
Total			53	100	100

Reasonably detailed information for both water resources and irrigation potential was available for 16 countries out of the total of 53 countries, or 30%. Reasonably detailed information on water resources only existed for 19 countries, on irrigation potential only for 21 countries.

As expected, in general, the least information was available for the more humid countries (category 3).

The table above is related to information available at country level. For the purpose of this study, it was necessary to have information for each basic unit, which refers to the different basin parts within a country. In total there are 136 basic units (Tables 1 and 2). For only 50 basic units, or 36%, reasonably detailed information was available. For 33 basic units, or 24%, partial information was available, while for the remaining 54 basic units, or 40%, no information was available.

In total, 38 countries are located within more than one basin, which means that there is more than one basic unit in the country (see chapter 2 and Table 2). Table 90 shows the availability of information on irrigation potential at the basic unit level for these 38 countries.

TABLE 89 Availability of information on irrigation potential at basic unit level

Degree of availability of information on irrigation potential at basic unit level	Countries with several basic units	Number of countries	% of total number of countries	% of irrigation potential
Reasonably detailed information available for each basic unit of the country	Botswana, Burkina Faso, Ethiopia, Kenya, Mali, Morocco, Niger, Nigeria, South Africa, Tanzania, Tunisia, Zambia, Zimbabwe.	13	34	30
Reasonably detailed information available or part of the basic units of the country	Algeria, Chad, Egypt, Eritrea, Libya, Madagascar, Malawi, Mauritania, Mozambique, Namibia, Senegal, Somalia, Sudan.	13	34	34
Little or no detailed information available at basic unit level of the country	Angola, Benin, Burundi, Cameroon, Central African Republic, Congo, Côte d'Ivoire, Djibouti, Guinea, Rwanda, Uganda, Zaire.	12	32	36
Total		38	100	100