As Israel prepares to carry out a unilateral partial pullback of its troops in Lebanon, an air of considerable uncertainty and unease prevails among Israeli troops and the Lebanese over what this step means for this already badly splintered land.

Israeli Army officers and spokesmen still do not seem to know what the "redeployment," as Israel calls it, will entail in terms of administration of the local population. Nor are they of one mind whether a pullback to the 20-yard-wide Awwali River on the northern outskirts of this city will result--as Lebanese and U.S. officials here say it could--in the de facto partition of the south from the north.

"There are a lot of questions about what redeployment will mean on the ground," one Army officer here said.

There is talk among Israeli officers and senior government officials here and in Jerusalem that "fences" and possibly even one long continuous "electronic fence" will be necessary all along the Awwali as part of a defense line to "hermetically seal off" the Israeli-occupied area against infiltration by "terrorists."

Yet, there is also an acute awareness among some that such a step is certain to be viewed in Lebanon and abroad as a consummation of this country's partition.

"In some areas, maybe we will have fences," said one Israeli military source in Jerusalem. "But a fence in and by itself won't do the job . . . . You cannot fence off the whole area and impose harsh conditions on the local population. It would create animosity . . . . This would mean partition de facto and we don't want it."

Other officers argue, however, that Lebanon is already partitioned into Syrian, Palestinian and Israeli spheres of influence and that a fence will not make that much difference.

Israeli Army spokesmen insist that there is no intention of turning southern Lebanon into an occupied territory similar to the West Bank or Gaza Strip. Israeli policy here, they say, is totally different from the policy in those areas, where there is a military administration over an officially recognized occupied territory.

"There is no parallel between south Lebanon and the West Bank, which is under military occupation," one Israeli officer said. Southern Lebanon "is not an area we consider to be under our occupation. We're there temporarily and we have no claims. We don't want an inch of territory."

He added, "We cannot and won't implement administrative measures the way we did in" the West Bank.

Despite these strong denials, the Israeli Army headquarters here in Sidon, the capital of southern Lebanon, is still in the building that once served as city hall and the main government center for southern Lebanon.

"We are de facto the administration in the south," one reserve officer doing his month-long service here remarked. He casually referred to the Israeli officer in charge of the liaison unit with the Lebanese as "governor."

The Lebanese government still handles civilian tasks such as water, public works, schools and health services. But the Israeli Army and the expanding militia of its local Christian ally, Maj. Saad Haddad, are in charge of virtually all security matters.

The Israelis still do not allow the remnants of a Lebanese Army brigade based here to leave the barracks with weapons or carry on any military activity despite Israel's official policy of trying to help the Lebanese Army and government assume their responsibilities.

"I have been teaching political science for 20 years," said the reserve officer, "but never have I experienced a situation like this."

In the year that Israel has occupied Lebanon up to the outskirts of Beirut, much has changed in the mood of its officers as casualties mount and the prospects for a total withdrawal in the near future recede.

Since the evacuation of the Palestinian guerrillas from Beirut last September, 145 Israeli soldiers have been killed in Lebanon, including about 40 in road accidents, and 368 injured. Altogether the invasion and occupation have cost Israel 502 lives and 2,794 injuries through June 15, according to the Army.

The most dangerous corridor for the Israeli Army has become the coastal road, particularly between Tyre and here, which Israeli soldiers have dubbed the "Ho Chi Minh Trail" because of the hostile activity along it. But many of the casualties have been inflicted in this city, a Sunni Moslem stronghold of about 200,000 inhabitants.

Thus it is not clear how much the pullback of the Israeli Army southward to the Awwali will do to relieve the security problem.

A day-long tour of the south with the Israeli Army makes it clear that the Army's overriding preoccupation has become the safety of its soldiers from the sporadic attacks, most of them carried out now by anti-Israeli Lebanese rather than Palestinian guerrillas, according to both Israeli Army and local Lebanese sources.

The change from a year ago is striking. Then a group of reporters taking a tour was accompanied by a single Israeli escort officer armed with an Uzi submachine gun, which he carried nonchalantly. There were no restrictions of movement or contact because the Army wanted to show visitors how warmly the local population was receiving them as "liberators" from the often unruly and dictatorial Palestinian guerrillas present in much of the south.

This time, reporters were required to wear flak jackets and each of the three cars in the convoy carried two soldiers who kept their rifles pointed out the window and on the ready. The cars were required to stay on certain main roads and there was little fraternizing with the people. A request to visit a Lebanese notable at his house on a back road was vetoed by the Army escort, citing security reasons.

Going through towns like Nabatiyah, Lebanon, is now viewed as extremely risky, particularly on market day when the streets are full of people, forcing cars to inch along and making them good targets.

Increased security precautions, including a ban on soldiers entering shops, has helped to cut Israeli casualties considerably in recent weeks. But officers say another factor in the decrease is Palestinian preoccupation with the factional fighting in Lebanon's eastern Bekaa Valley.

This explanation does not seem to square with Israeli and Lebanese intelligence reports that most of the hit-and-run attacks now are being carried out by Lebanese, increasingly Shiites who belong to the extreme pro-Iranian faction of Amal, the main Shiite organization in Lebanon.

In an interview at his headquarters in Marjuyun, Haddad, whose militia is a prime source of Israeli intelligence, said these "Khomeinists" were a small minority in the south but responsible for most of the attacks.

One of the main Israeli concerns here is that Amal will turn against both Haddad's militia and the Israeli Army if it is obliged to remain in southern Lebanon. There is still more cooperation than antagonism between the two, but Amal leaders have warned this could easily change if the Israelis become "occupiers."

Already, there are indications the mood among the Shiites, who are the largest ethnic group in the south and provide at least 50 percent of Haddad's 1,000-man militia force in the villages, may be changing as the prospects for a longer Israeli occupation increase.

One Shiite businessman here close to the Amal leadership in Sidon was asked whether he did not prefer the Israeli presence to the former Palestinian guerrilla presence in the south. He replied, as four Israeli soldiers listened: "It all boils down to just an occupation. I prefer Lebanese occupation."

His main complaint--other than bad business because of the uncertainty of the situation--was the continued Israeli Army occupation of Sidon's city hall, which he said had caused "alot of headaches" for the local people.

Asked what would be the local reaction if Israel pulled back to the Awwali instead of withdrawing totally, he said increased resentment would be "a natural thing."

"If they think twice about it, they will just leave and be a good neighbor," he said. "The people here want the Lebanese government to return. They will all help it."

"Just leave," he said, "and we will fight the Syrians."