Restoration of natural watercourses to reduce water deficit on sodic wetland system in the Hortobágy

Introduction

The 2,933-hectare Pannonic salt steppes and salt marshes and Pannonic loess steppes project area developed a significant water deficit. The combined effects of regional rainwater drawdown and climate change have resulted in 1.1-1.5 million m³ less rainwater entering the project area each year.

Wetland Status

The status of the wetlands of the 15 sodic wetlands has changed unfavorably. The proportion of dry habitat mosaics in the riverbeds was:

• 2% in the reference state
• Increased to 33% today

The healthy water balance was further upset by the proliferation of problematic non-native and native trees and shrubs with water consumption higher than that of the original plant communities, as well as the proliferation of reed and cattail.

Soil and Water Dynamics

The loosening of the riverbed and the compaction of the soils of direct catchments also had an adverse effect. This has led to:

1. A further decrease of the residence time of the water
2. Increased sedimentation of the beds

In sum, an unfavorable steppification process has started to take place, significantly damaging the conservation status of the sodic wetland sub-type of 1530 habitat. This has reduced the population of priority bird species characteristic of these habitats by 300-400% and impaired ecosystem services.

Project Goals

The primary goal of the project is to tackle the problem of reduced water deficit in the 15 sodic wetlands. This can be achieved by:

• Supplementing the precipitation from the direct catchment with the annual 1.1-1.5 million m³ of rainwater generated in the 6,000-hectare catchment
• Discharging this water into the 15 water bodies by restored watercourses

As a result, in wetland beds, the sub-type habitat will return to the reference status level on average. In particular, the proportion of dry sodic habitats will decrease from today's 33% to 5% by the end of the project period.

Expected Outcomes

As a further effect, the number of priority breeding and migratory bird species will also increase to at least 90-95% of the potential carrying capacity.