**3. Results**

*Sustainability Assessment at the 21st Century*

mean depth—0.45 m., volume—0.44 × 106

fauna emphasizing aquatic birds.

the mid-1990s, a daily volume of 25 × 103

mation project (HRP) was consequently implemented.

**1.2 A brief historical survey of the Hula Valley management**

During the last 80 years, the Lake Kinneret drainage basin ecosystems have undergone significant anthropogenic and natural modifications. Prior to the 1950s, the Hula Valley was mostly (6500 ha) covered with old Lake Hula (1300 ha) and swampy wetlands. This area was not cultivated, malaria was common, and water loss by evapotranspiration (ET) was significant. The Jordan River crossing the Hula Valley contributes about 63% of the downstream of the Lake Kinneret's water budget, but 70% of the total nutrient inputs, of which over 50% originate in the Hula Valley region, including the valley and the slopes on both sides (east and west) of it. Old Lake Hula and swamps were drained and were being converted for agricultural development. Years later, land utilization was modified in an operation referred to as the Hula Reclamation Project (HRP) which was improved later. The HRP included creation of a new shallow lake Agmon (surface area of 1120 ha,

m3

Prior to the drainage of old Lake Hula and adjacent swamps during 1950–1957, Nitrogen was fluxed from the basin to the lake, mostly as highly bioavailable ammonia, but after the Hula drainage, the dominant N was modified to nitrate. Before

m3

The aim of the present paper is to evaluate the outcome of the anthropogenic intervention in the Hula Valley, together with climate change, on the management of Lake Kinneret, its water quality, and the entire ecosystem structure trait.

Climatological (precipitation, air temperature) data was supported by the Israeli Meteoroloical Service. Jordan River discharge and nutrient concentrations were supported by Kinneret Limnological Labortory Data Base and Mekorot Water Supply Company Jordan District. The nutrient concentrations and the phytoplankton composition structure in the epilimnion of Lake Kinneret during 1970–2018, as well as water level and ground water table (GWT) in the Hula Valley were all reevaluated and statistically analyzed. The information was given by Kinneret

effluents rich with ammonia fluxed into Lake Kinneret. The fishpond area was dramatically reduced (450 ha), as well as its effluents, and the raw sewage was stored in reservoirs and reused. As a result of inappropriate irrigation and agricultural methods, the peat soil quality deteriorated by consolidation, destruction, and surface subsidence. It was accompanied by heavy dust storms, blocking of drainage canals, enhancement of underground fires, and outbreaks of rodent populations. These deteriorated processes caused severe damage to agricultural crops. A recla-

water supply canals, placing a vertical plastic barrier along 2.8 km crossing the valley from east to west, maintenance of higher underground water table, and functional conversion of 500 ha with lake Agmon in the center from agricultural to eco-tourism usage. The objectives of HPR were aimed at: (1) nutrient removal from the Lake Kinneret external loads through the Lake Agmon hydrological system; (2) to produce an ecological component for eco-tourism-Lake Agmon; and (3) the usage of Lake Agmon as a principal component for the hydrological management and agricultural irrigation system for the entire valley. The following objectives were implemented: improvement of irrigation water supply, maintenance of high underground water table ensuring peat soil moisture to prevent its deterioration, and the achievement of a high diversity of re-establishment of natural flora and

), renewal of 90 km drainage and

of raw sewage and fishpond (1700 ha)

**128**

**2. Methods**

#### **3.1 Climate change**

The periodical occurrence of drought is given in **Table 1**. Results in **Table 1** indicate 62% periods (years) of three levels (A, B, and C) drought as SPI (specific precipitation index) values [1] during 1930–1980, and 42% during 1981–2014. Moreover, percentage of normal conditioned periods was higher during the latter period. Nevertheless, recent 5 years (2014–2018) were consecutive drought seasons.

Data shown in **Figure 3** indicate precipitation decline since mid-1980s. The information that is evaluated in **Figure 1** was collected (from 1940) in the Dafna Station located in northern Hula Valley statistically indicating a decline of appox. 140 mm annually.

Periodical means of air temperatures measured in the meteorological Station in Dafna (Northern Hula Valley) during 62 years (1946–2008) resulted (°C) in the following changes: 20.2, 19.4, 18.9, and 19.8 in 1946–1958, 1959–1982, 1983–1990, and 1991–2008, respectively, indicating fluctuation ranges of −0.8, −0.5, and +0.9°C.


*A—close to normal conditions; B—moderate drought; C—severe drought; and D—normal conditions.*

#### **Table 1.**

*Drought level (A, B, C, and D) occurrence (%) evaluated as SPI values [1].*

#### **Figure 1.**

*Trend of changes (LOWESS; 0.8) of daily maxima (left panel) and minima (right panel) of air temperature (°C) Dafna Station (Northern Hula Valley) during 1969–2001.*

LOWESS smoothing statistical method provide locally weighted scatterplot smoothing. The smoothed values are obtained by running a regression of Y and X variables weighted where the central value gets the highest weight and other points around receive less weight. Moreover, in relation to those documented air temperature change, the lake water temperatures were fluctuated as well (**Figure 2**): The upper epilimnetic layer (0–10 m) became warmer since the early 1980s until the early 2000s by 1.9 (21.7–23.6), whilet the temperature increased in the lower layer (32 m deep) similarly by app 2.0°C but reasonably later (from late 1980s) (**Figure 2**).

A significant evidence for climate change is given in **Figure 3**, which represents a mean increase of 60 mm from 1940 until the mid-1980s and later a decline of app. 130 mm until present.
