MUKALLA, 8 December 2008 (IRIN) - Agricultural experts, government officials and local communities in Hadramaut Governorate, southern Yemen, are urging the government to tackle an evergreen and fast-growing shrub which has been blocking waterways, with sometimes devastating consequences.

They say the shrub is responsible for exacerbating the late October floods by blocking watercourses and diverting floodwater into villages which might otherwise have been unscathed. At least 90 people were killed, and 20,000-25,000 were made homeless by the floods.

The governor of Hadramaut, Salem al-Khanbishi, told IRIN the shrub must be eradicated. "We must find a quick solution to the shrubs; they're one of the reasons for the recent disaster in the governorate. NGOs and the government must work together to uproot them," he said.

Prosopis juliflora - commonly known as Mesquite and introduced several decades ago to combat desertification and stabilise sand dunes - is native to the Americas, tolerates harsh, arid, saline conditions, and has spread throughout arable parts of Hadramaut.

In Wadi Hajar, a sandy river valley with permanently running water that drains into the Gulf of Aden west of Mukalla, the whole watercourse system and its associated sandy fringes have been stabilised by the planting of the shrub, say experts.

But the shrub has recently colonised many uncultivated hectares of land in Yemen's coastal and eastern desert areas, with animals responsible for the spread: The seeds are mainly disseminated in animal droppings.

When left unmanaged the shrub can form dense impassable thickets, particularly where land has been degraded or overgrazed, say agricultural experts. It also invades cultivated fields and irrigated farms.

Water diverted

Hadramaut residents say thickets of the shrub blocked and then changed the course of water channels during the October flooding, with devastating effects.

Residents of Thuba, a village 25km east of Seyoun, which was severely hit by the floods, said their village would not have been affected had the nearest watercourse been free of the shrub. Thousands of the shrubs stood in the floods' way, diverting floodwater into their village.

Nasser al-Tamimi], a resident of Thuba, told IRIN: "We have been calling for immediate action against the shrubs since 2002 when earlier floods destroyed many houses, but the shrubs were left unchecked. If the government doesn't take any action to stop the spread of the trees shrubs, similar disasters will happen in future," he said.

Farmers consider the shrub an evil: The bushy plants have invaded the land, forming dense, impenetrable thickets, and rendering thousands of hectares unsuitable for agriculture.

Ahmed Bataher, an agronomist with the Yemeni government's Agricultural Research Station, told IRIN the threat posed by the shrub lay in its ability to withstand the harsh, dry climate of Hadramaut. "Now there are thousands of the shrubs spreading along the wide valley; it'll take years to rid Hadramaut of them. We can benefit from [Central and South] American countries' know-how on how best to tackle the shrubs," he said.

The shrub is used by rural communities and the urban poor In Hadramaut to satisfy their domestic firewood needs. Herdsmen also use it as a forage supplement for their herds.

Bataher favours managing the spread of the shrub: "Many people depend on the trees for wood. We should remove only those trees that have invaded river valleys."

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